[release/9.0] Ensure that Vector128.CreateSequence works on x86 for non-constant 64-bit inputs

[github-actions]

Backport of #107053 to release/9.0

/cc @tannergooding

Customer Impact

• Customer reported
• Found internally

Found by Antigen: #106372

Developers using the new vector CreateSequence API for long or ulong on an x86 machine would see incorrect results.

Regression

• Yes
• No

This is a new API in .NET 9 and a scenario that was missed for non-constant inputs on 32-bit hardware.

Testing

An explicit regression test was added and additional code paths were checked to ensure they were correctly handling the inputs.

Risk

Low. This is a net new API in .NET 9 and is simply falling back to the managed code path for 32-bit hardware, as expected.

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[tannergooding]

CC. @dotnet/jit-contrib, @EgorBo

[tannergooding]

Closed and reopened to get CI to start, its going now

[jeffschwMSFT]

approved. we can merge when ready

[jeffschwMSFT]

@tannergooding can you take a look at the PR failures?

[tannergooding]

@jeffschwMSFT, they are unrelated flaky tests and passed on rerun. -- They are variations of the general exit code 137 failure that has several tracking issues already (https://github.com/dotnet/runtime/issues?q=is%3Aissue+is%3Aopen+exit+code+137+)