[API Implementation]: Add Microseconds and Nanoseconds to TimeStamp, DateTime, DateTimeOffset, and TimeOnly

[deeprobin]

Proposal implementation of #23799 (closes #23799)

Proposal

namespace System {
    public struct DateTime {
        public DateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond);
        public DateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond, DateTimeKind kind);
        public DateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond, Calendar calendar);
        public int Microsecond { get; }
        public int Nanosecond { get; }
        public DateTime AddMicroseconds(double value);
    }
    public struct DateTimeOffset {
        public DateTimeOffset(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond, TimeSpan offset);
        public DateTimeOffset(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond, TimeSpan offset, Calendar calendar);
        public int Microsecond { get; }
        public int Nanosecond { get; }
        public DateTimeOffset AddMicroseconds(double value);
    }
    public struct TimeSpan {
        public const long TicksPerMicrosecond;
        public const long NanosecondsPerTick;
        public TimeSpan(int days, int hours, int minutes, int seconds, int milliseconds, int microseconds);
        public int Microseconds { get; }
        public int Nanoseconds { get; }
        public double TotalMicroseconds { get; }
        public double TotalNanoseconds { get; }
        public static TimeSpan FromMicroseconds(double value);
    }
    public struct TimeOnly {
        public TimeOnly(int day, int hour, int minute, int second, int millisecond, int microsecond);
        public int Microsecond { get; }
        public int Nanosecond { get; }
    }
}

Current state of implementation

• Proposal logic / implementation
• Ref Assembly
• Tests

/cc @tarekgh
/cc @ChristopherHaws

[dotnet-issue-labeler]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, to please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[deeprobin]

It should be mentioned that I have taken the documentation comments from the current documentation and adapted them accordingly.

I have extended the current test cases accordingly. I assume that these are not flaky.

[ghost]

Tagging subscribers to this area: @dotnet/area-system-runtime
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Proposal implementation of #23799 (closes #23799)

Proposal

namespace System {
    public struct DateTime {
        public DateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond);
        public DateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond, DateTimeKind kind);
        public DateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond, Calendar calendar);
        public int Microsecond { get; }
        public int Nanosecond { get; }
        public DateTime AddMicroseconds(double value);
    }
    public struct DateTimeOffset {
        public DateTimeOffset(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond, TimeSpan offset);
        public DateTimeOffset(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond, TimeSpan offset, Calendar calendar);
        public int Microsecond { get; }
        public int Nanosecond { get; }
        public DateTimeOffset AddMicroseconds(double value);
    }
    public struct TimeSpan {
        public const long TicksPerMicrosecond;
        public const long NanosecondsPerTick;
        public TimeSpan(int days, int hours, int minutes, int seconds, int milliseconds, int microseconds);
        public int Microseconds { get; }
        public int Nanoseconds { get; }
        public double TotalMicroseconds { get; }
        public double TotalNanoseconds { get; }
        public static TimeSpan FromMicroseconds(double value);
    }
    public struct TimeOnly {
        public TimeOnly(int day, int hour, int minute, int second, int millisecond, int microsecond);
        public int Microsecond { get; }
        public int Nanosecond { get; }
    }
}

Current state of implementation

• Proposal logic / implementation
• Ref Assembly
• Tests

/cc @tarekgh
/cc @ChristopherHaws

Author:	deeprobin
Assignees:	-
Labels:	area-System.Runtime, new-api-needs-documentation, community-contribution
Milestone:	-

[tarekgh]

@deeprobin I'll try to take a look at this PR later today and will get back to you.

[danmoseley]

@deeprobin you might be interested to check that your tests are giving full code coverage of your code:

runtime/docs/workflow/building/libraries/code-coverage.md

Line 53 in b248950

## Code coverage with System.Private.CoreLib code

[deeprobin]

@danmoseley
Thanks. I can take a look at that after the other open questions have been clarified here :).

[tarekgh]

Could you please add tests for TimeSpan new APIs? Also, when writing these tests please ensure using negative values in addition to positive values.

[tarekgh]

@deeprobin I left some comments I hope you can address them soon. After that we should be good to go. great work!

[joperezr]

/azp run runtime (Rerunning CI in order to fetch changes merged in main which have fixed the Regex test)

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[tarekgh]

@deeprobin will be able to address the remaining feedback soon?

[tarekgh]

The failing test is unrelated and is tracked by the issue #67878

[ChristopherHaws]

🎉 Thanks for implementing this @deeprobin!