perf: Add a zero-allocation version of the API

[atifaziz]

This is a follow-up to PR #8

Incidentally, do you care to also add this? This way, the allocation of string becomes the entire responsibility of the caller, but it will require a modest expansion to the public API. Let me know if you're interested and I can propose something for prosperity, when I am bored next.

I'm interested.

This PR renames Utf8String to Chars, makes it (mostly) public, and adds the following new zero-allocation APIs:

public static void Generate(MonikerStyle monikerStyle, out Chars adjective, out Chars noun) { /* … */ }
public static void GenerateMoniker(out Chars adjective, out Chars noun) { /* … */ }
public static void GenerateMoby(out Chars adjective, out Chars noun) { /* … */ }

Unfortunately, since generic value tuples cannot carry Chars, one cannot simply return (Chars, Chars) or (Chars Adjective, Chars Noun) so out parameters are used instead. The other way to solve this would be to introduce a CharsPair type, but that would just add more code to maintain and test, and bring marginal benefits (though it can always be done later too).

Utf8String is renamed to Chars to encapsulate how data is stored internally. It has methods that permit writing into char and UTF-8 byte buffers for those who care to avoid an allocation; for those who don't care can simply call ToString().

The benchmarks are updated and show roughly a 5x performance increase and zero allocations with the new members:

Method	Mean	Error	StdDev	Median	Gen0	Allocated
GenerateMoby	58.53 ns	0.783 ns	0.694 ns	58.51 ns	0.0043	55 B
GenerateMoniker	59.96 ns	1.762 ns	5.166 ns	57.31 ns	0.0042	53 B
GenerateMobyPair	11.84 ns	0.221 ns	0.246 ns	11.85 ns	-	-
GenerateMonikerPair	12.44 ns	0.271 ns	0.535 ns	12.22 ns	-	-

---

• BenchmarkDotNet v0.14.0, Windows 11 (10.0.22631.4037/23H2/2023Update/SunValley3)
• 13th Gen Intel Core i7-1370P, 1 CPU, 20 logical and 14 physical cores
• .NET SDK 8.0.400
  • [Host] : .NET 8.0.8 (8.0.824.36612), X64 RyuJIT AVX2
  • DefaultJob : .NET 8.0.8 (8.0.824.36612), X64 RyuJIT AVX2

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[alexmg]

Thanks for the additional contribution @atifaziz! 👍