Replace internal option–voption conversions with FSharp.Core funcs

[brianrourkeboll]

Description

Reprise of #17457, now that FSharp.Core 9 has shipped.

• Remove internal option–voption conversion functions in this repo and replace their usage with the FSharp.Core ones added in Module functions for 'T option ↔ 'T voption #17436.

Resolves #17460.

Checklist

• These changes are internal only, so release notes shouldn't be needed.

[github-actions]

❗ Release notes required

@brianrourkeboll,

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Change path	Release notes path	Description
src/Compiler	docs/release-notes/.FSharp.Compiler.Service/9.0.300.md	No release notes found or release notes format is not correct
vsintegration/src	docs/release-notes/.VisualStudio/17.14.md	No release notes found or release notes format is not correct