Optimize bit operations of BigInteger

[kzrnm]

This PR is a refactored version of #112632.

Benchmark

BenchmarkDotNet v0.13.12, Windows 11 (10.0.26100.3194)
13th Gen Intel Core i5-13500, 1 CPU, 20 logical and 14 physical cores
.NET SDK 10.0.100-preview.3.25125.5
  [Host]     : .NET 10.0.0 (10.0.25.12411), X64 RyuJIT AVX2
  Job-MGDTRH : .NET 10.0.0 (42.42.42.42424), X64 RyuJIT AVX2
  Job-TRYYFZ : .NET 10.0.0 (42.42.42.42424), X64 RyuJIT AVX2
  Job-BFYRFS : .NET 10.0.0 (42.42.42.42424), X64 RyuJIT AVX2

Method	Toolchain	Mean	Ratio	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
PositiveLeftShift	\main\corerun.exe	13.150 ms	1.00	62.5000	62.5000	62.5000	33 MB	1.00
PositiveLeftShift	\vectorize\corerun.exe	6.654 ms	0.48	156.2500	156.2500	156.2500	33 MB	1.00
PositiveLeftShift	\scalar\corerun.exe	8.763 ms	0.64	156.2500	156.2500	156.2500	33 MB	1.00
NegativeLeftShift	\main\corerun.exe	12.914 ms	1.00	78.1250	78.1250	78.1250	33 MB	1.00
NegativeLeftShift	\vectorize\corerun.exe	6.559 ms	0.50	156.2500	156.2500	156.2500	33 MB	1.00
NegativeLeftShift	\scalar\corerun.exe	8.794 ms	0.68	156.2500	156.2500	156.2500	33 MB	1.00
PositiveRightShift	\main\corerun.exe	15.399 ms	1.00	125.0000	125.0000	125.0000	31 MB	1.00
PositiveRightShift	\vectorize\corerun.exe	9.417 ms	0.61	187.5000	187.5000	187.5000	31 MB	1.00
PositiveRightShift	\scalar\corerun.exe	11.450 ms	0.74	187.5000	187.5000	187.5000	31 MB	1.00
NegativeRightShift	\main\corerun.exe	19.945 ms	1.00	125.0000	125.0000	125.0000	31 MB	1.00
NegativeRightShift	\vectorize\corerun.exe	9.426 ms	0.48	187.5000	187.5000	187.5000	31 MB	1.00
NegativeRightShift	\scalar\corerun.exe	11.648 ms	0.58	187.5000	187.5000	187.5000	31 MB	1.00
PositiveUnsignedRightShift	\main\corerun.exe	14.067 ms	1.00	125.0000	125.0000	125.0000	31 MB	1.00
PositiveUnsignedRightShift	\vectorize\corerun.exe	9.431 ms	0.67	187.5000	187.5000	187.5000	31 MB	1.00
PositiveUnsignedRightShift	\scalar\corerun.exe	11.628 ms	0.83	187.5000	187.5000	187.5000	31 MB	1.00
NegativeUnsignedRightShift	\main\corerun.exe	16.347 ms	1.00	125.0000	125.0000	125.0000	31 MB	1.00
NegativeUnsignedRightShift	\vectorize\corerun.exe	11.230 ms	0.69	187.5000	187.5000	187.5000	31 MB	1.00
NegativeUnsignedRightShift	\scalar\corerun.exe	13.608 ms	0.83	187.5000	187.5000	187.5000	31 MB	1.00
PositiveRotateLeft	\main\corerun.exe	13.674 ms	1.00	125.0000	125.0000	125.0000	32 MB	1.00
PositiveRotateLeft	\vectorize\corerun.exe	10.775 ms	0.79	187.5000	187.5000	187.5000	32 MB	1.00
PositiveRotateLeft	\scalar\corerun.exe	13.057 ms	0.96	187.5000	187.5000	187.5000	32 MB	1.00
NegativeRotateLeft	\main\corerun.exe	18.040 ms	1.00	125.0000	125.0000	125.0000	32 MB	1.00
NegativeRotateLeft	\vectorize\corerun.exe	14.679 ms	0.83	187.5000	187.5000	187.5000	32 MB	1.00
NegativeRotateLeft	\scalar\corerun.exe	17.039 ms	0.94	187.5000	187.5000	187.5000	32 MB	1.00
PositiveRotateRight	\main\corerun.exe	13.671 ms	1.00	125.0000	125.0000	125.0000	32 MB	1.00
PositiveRotateRight	\vectorize\corerun.exe	10.651 ms	0.78	187.5000	187.5000	187.5000	32 MB	1.00
PositiveRotateRight	\scalar\corerun.exe	13.071 ms	0.96	187.5000	187.5000	187.5000	32 MB	1.00
NegativeRotateRight	\main\corerun.exe	16.000 ms	1.00	125.0000	125.0000	125.0000	32 MB	1.00
NegativeRotateRight	\vectorize\corerun.exe	12.632 ms	0.79	187.5000	187.5000	187.5000	32 MB	1.00
NegativeRotateRight	\scalar\corerun.exe	14.861 ms	0.93	187.5000	187.5000	187.5000	32 MB	1.00

<details>

<summary>benchmark code</summary>

```cs
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Configs;
using System.Numerics;

[MemoryDiagnoser(false)]
[HideColumns("Job", "Error", "StdDev", "Median", "RatioSD")]
public class ShiftTest
{
    const int shiftSize = (1 << 23) + 13;
    BigInteger positive, negative;

    [GlobalSetup]
    public void Setup()
    {
        var bytes = new byte[1 << 25];
        new Random(227).NextBytes(bytes);
        positive = new BigInteger(bytes, isUnsigned: true);
        negative = -positive;
    }

    [Benchmark] public BigInteger PositiveLeftShift() => positive << shiftSize;
    [Benchmark] public BigInteger NegativeLeftShift() => negative << shiftSize;

    [Benchmark] public BigInteger PositiveRightShift() => positive >> shiftSize;
    [Benchmark] public BigInteger NegativeRightShift() => negative >> shiftSize;

    [Benchmark] public BigInteger PositiveUnsignedRightShift() => positive >>> shiftSize;
    [Benchmark] public BigInteger NegativeUnsignedRightShift() => negative >>> shiftSize;

    [Benchmark] public BigInteger PositiveRotateLeft() => BigInteger.RotateLeft(positive, shiftSize);
    [Benchmark] public BigInteger NegativeRotateLeft() => BigInteger.RotateLeft(negative, shiftSize);

    [Benchmark] public BigInteger PositiveRotateRight() => BigInteger.RotateRight(positive, shiftSize);
    [Benchmark] public BigInteger NegativeRotateRight() => BigInteger.RotateRight(negative, shiftSize);
}

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[jeffhandley]

@tannergooding I know we've talked (for a long time) about substantial overhauls (rewrites) of how BigInteger is implemented, and I have been sitting on this PR (sorry, @kzrnm) for a long time because I've been unsure if we should take incremental but still sizeable changes. I'm inclined to accept this change though, even if we do end up doing more substantial work later. What do you think?