DateTime: Use Optimised Equals Implementation in object.Equals()

[Sewer56]

• This picks up from Optimize DateTime.Equals #59857 , adding the new equals implementation to the object.Equals() method, since previously the old implementation was still intact there.

Codegen Diff: https://www.diffchecker.com/O0mRKfb6 (-21 bytes)

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Setup:

BenchmarkDotNet=v0.13.1.1847-nightly, OS=Windows 10 (10.0.19044.2075/21H2/November2021Update)
Intel Core i7-4790K CPU 4.00GHz (Haswell), 1 CPU, 8 logical and 4 physical cores
.NET SDK=7.0.100-rtm.22480.6
  [Host]     : .NET 7.0.0 (7.0.22.47809), X64 RyuJIT AVX2

Before:

py scripts\benchmarks_ci.py -f net7.0 --bdn-arguments="--artifacts "C:\results\latest_sdk"" --filter System.Tests.Perf_DateTime.Equals*

Job-NDINMX : .NET 7.0.0 (7.0.22.47809), X64 RyuJIT AVX2

PowerPlanMode=00000000-0000-0000-0000-000000000000  IterationTime=250.0000 ms  MaxIterationCount=20  
MinIterationCount=15  WarmupCount=1  

|       Method |     Mean |     Error |    StdDev |   Median |      Min |      Max | Code Size | Allocated |
|------------- |---------:|----------:|----------:|---------:|---------:|---------:|----------:|----------:|
| ObjectEquals | 1.392 ns | 0.0169 ns | 0.0150 ns | 1.389 ns | 1.365 ns | 1.420 ns |     210 B |         - |

After:

py scripts\benchmarks_ci.py -f net7.0 --bdn-arguments="--artifacts "C:\results\dev" -d" --filter System.Tests.Perf_DateTime.ObjectEquals* --corerun "C:\Users\sewer\Desktop\Projects\runtime\artifacts\bin\testhost\net7.0-windows-Release-x64\shared\Microsoft.NETCore.App\8.0.0\corerun.exe"

Job-YQMWEN : .NET 8.0.0 (42.42.42.42424), X64 RyuJIT AVX2

PowerPlanMode=00000000-0000-0000-0000-000000000000  Toolchain=CoreRun  IterationTime=250.0000 ms  
MaxIterationCount=20  MinIterationCount=15  WarmupCount=1  

|       Method |      Mean |     Error |    StdDev |    Median |       Min |       Max | Code Size | Allocated |
|------------- |----------:|----------:|----------:|----------:|----------:|----------:|----------:|----------:|
| ObjectEquals | 0.6923 ns | 0.0073 ns | 0.0061 ns | 0.6915 ns | 0.6826 ns | 0.7062 ns |     189 B |         - |

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Benchmark: Sewer56/performance@2a762e3
dotnet/performance: dotnet/performance#2626

[ghost]

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.

[EgorBo]

@Sewer56 thanks!