Return ValueTask instead of Task for read/write APIs.

[habbes]

Issues

This pull request fixes #2816 .

Description

Refactor read/write APIs to return ValueTask instead of Task to improve performance and reduce allocations. This PR targets read and write APIs because those are buffered and may complete synchronously most of the time. This PR also only target the core library and not the client. This PR does not change all async APIs from Task to ValueTask, some APIs are intentional left as-is, for example in the following scenarios:

• FlushAsync() methods still return Task. We don't expect FlushAsync() to complete synchronously because the method is intended to force the I/O operation.
• Read/Write methods that override standard API methods that return Task (e.g. when inheriting from TextWriter).

Here are classes where I have made changes from Task to ValueTask. Let me know if I missed any:

• IJsonWriter
• IJsonReader
• JsonWriter
• ODataUtf8JsonWriter and its nested classes
• ODataOutputContext
• ODataMessageWriter
• ODataInputContext
• ...

TODO: refactor or remove the custom FollowOnSuccessWith and FollowAlwaysMethod and other TaskUtils helpers.

Removed ValidateBufferArguments from TranscodingWriteStream method because it's now inherited from Stream. We should also remove our the custom TranscodingWriteStream and replace it with the built-in one.

Benchmarks before

Method	WriterName	Mean	Error	StdDev	Median	Gen 0	Gen 1	Allocated
WriteToFileAsync	JsonSerializer	26.83 ms	0.534 ms	0.799 ms	26.80 ms	-	-	3,289 B
WriteToFileAsync	ODataMessageWriter	105.21 ms	2.639 ms	7.443 ms	103.41 ms	15800.0000	200.0000	68,851,538 B
WriteToFileAsync	ODataMessageWriter-Async	176.06 ms	4.141 ms	11.679 ms	173.24 ms	20000.0000	1000.0000	86,382,176 B
WriteToFileAsync	ODataMessageWriter-NoValidation	97.20 ms	2.647 ms	7.552 ms	95.41 ms	15000.0000	-	68,852,552 B
WriteToFileAsync	ODataMessageWriter-NoValidation-Async	157.68 ms	3.124 ms	8.339 ms	155.84 ms	20000.0000	1000.0000	86,378,832 B
WriteToFileAsync	ODataMessageWriter-Utf8JsonWriter	89.85 ms	1.151 ms	2.299 ms	89.27 ms	15000.0000	-	66,144,584 B
WriteToFileAsync	ODataMessageWriter-Utf8JsonWriter-Async	139.12 ms	2.770 ms	7.345 ms	138.23 ms	15000.0000	-	66,516,616 B
WriteToFileAsync	ODataMessageWriter-Utf8JsonWriter-NoValidation	82.96 ms	2.212 ms	6.417 ms	80.30 ms	15000.0000	-	66,141,240 B
WriteToFileAsync	ODataMessageWriter-Utf8JsonWriter-NoValidation-Async	120.10 ms	2.370 ms	5.398 ms	118.73 ms	15000.0000	-	66,513,272 B
WriteToFileWithLargeValuesAsync	JsonSerializer	305.32 ms	5.825 ms	7.574 ms	306.77 ms	-	-	-
WriteToFileWithLargeValuesAsync	ODataMessageWriter	400.29 ms	16.450 ms	47.984 ms	382.67 ms	-	-	239,168 B
WriteToFileWithLargeValuesAsync	ODataMessageWriter-Async	1,250.57 ms	29.237 ms	84.356 ms	1,229.95 ms	490000.0000	-	2,113,979,832 B
WriteToFileWithLargeValuesAsync	ODataMessageWriter-NoValidation	342.92 ms	7.624 ms	21.504 ms	337.85 ms	-	-	237,160 B
WriteToFileWithLargeValuesAsync	ODataMessageWriter-NoValidation-Async	1,115.87 ms	17.410 ms	14.538 ms	1,113.62 ms	490000.0000	-	2,113,978,240 B
WriteToFileWithLargeValuesAsync	ODataMessageWriter-Utf8JsonWriter	197.86 ms	4.726 ms	13.636 ms	196.58 ms	-	-	226,456 B
WriteToFileWithLargeValuesAsync	ODataMessageWriter-Utf8JsonWriter-Async	264.63 ms	7.449 ms	21.372 ms	258.54 ms	-	-	2,096,688 B
WriteToFileWithLargeValuesAsync	ODataMessageWriter-Utf8JsonWriter-NoValidation	206.98 ms	4.500 ms	13.126 ms	205.95 ms	-	-	224,784 B
WriteToFileWithLargeValuesAsync	ODataMessageWriter-Utf8JsonWriter-NoValidation-Async	263.91 ms	6.069 ms	17.512 ms	264.12 ms	-	-	2,095,936 B

Method	propertyType	Mean	Error	StdDev	Median	Gen 0	Gen 1	Gen 2	Allocated
WriteFeed	Entit(...)etSet [23]	87.97 ms	2.777 ms	8.011 ms	85.86 ms	4000.0000	-	-	20.55 MB
WriteFeed	EntityDecimalSet	91.31 ms	1.821 ms	5.016 ms	89.29 ms	4000.0000	-	-	19.02 MB
WriteFeed	EntityGuidSet	66.00 ms	1.285 ms	2.596 ms	65.04 ms	5000.0000	-	-	22.07 MB
WriteFeed	EntityInt32Set	59.73 ms	1.192 ms	2.435 ms	59.23 ms	3000.0000	-	-	12.92 MB
WriteFeed	EntityInt64Set	62.82 ms	1.251 ms	2.974 ms	61.54 ms	3000.0000	-	-	15.97 MB
WriteFeed	EntityMixedSet	49.27 ms	0.982 ms	0.767 ms	49.22 ms	2000.0000	-	-	10.93 MB
WriteFeed	EntityStringSet	62.84 ms	0.964 ms	0.805 ms	62.80 ms	-	-	-	3.76 MB

Checklist (Uncheck if it is not completed)

• Test cases added
• Build and test with one-click build and test script passed

Additional work necessary

If documentation update is needed, please add "Docs Needed" label to the issue and provide details about the required document change in the issue.

[habbes]

Closing because I've picked up the work in a different PR: #2975