Use TryParseUInt32HexNumberStyle directly from Guid.TryParse

[stephentoub]

Skips public entry points of uint.TryParse, including argument validation, branches for style, but most impactfully fetching the current number culture when it won't actually be needed.

Noticed while looking at startup costs, as it was causing current culture to be initialized unexpectedly.

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Diagnosers;
using BenchmarkDotNet.Running;
using System;

[MemoryDiagnoser]
public class Program
{
    static void Main(string[] args) => BenchmarkSwitcher.FromAssemblies(new[] { typeof(Program).Assembly }).Run(args);

    [Benchmark]
    public bool TryParse() => Guid.TryParse("dd16f057-4f29-495c-9f09-7201d8bee53d", out _);

    [Benchmark]
    public bool TryParseD() => Guid.TryParseExact("dd16f057-4f29-495c-9f09-7201d8bee53d", "D", out _);

    [Benchmark]
    public bool TryParseN() => Guid.TryParseExact("6e76bbd10361464b980309a281d17180", "N", out _);
}

Method	Toolchain	Mean	Ratio
TryParse	\master\corerun.exe	86.38 ns	1.00
TryParse	\pr\corerun.exe	74.42 ns	0.87
TryParseD	\master\corerun.exe	82.14 ns	1.00
TryParseD	\pr\corerun.exe	71.21 ns	0.89
TryParseN	\master\corerun.exe	96.77 ns	1.00
TryParseN	\pr\corerun.exe	60.36 ns	0.62

Contributes to #44598

[danmoseley]

Do we already have micro benchmark coverage?

[stephentoub]

https://github.com/dotnet/performance/blob/3852eed29114cbc771301f1c893445234d4a0d00/src/benchmarks/micro/libraries/System.Runtime/Perf.Guid.cs#L48

[kunalspathak]

Perf lab data shows improvements - DrewScoggins/performance-2#3513