[DedSec256]

Adds LangVersionText: string to FSharpProjectSnapshot and ProjectConfig. For the same options it returns what FSharpParsingOptions.LangVersionText does.

Depends on #: it uses CompilerOptions.ParseCompilerOption from there.

Changes

• ProjectConfig.LangVersionText is computed lazily from OtherOptions. It is the last --langversion the compiler accepts, otherwise default. An unrecognized or out-of-support version is skipped, the same way TcConfigBuilder keeps its previous version when it reports the error. It is exposed through ProjectSnapshotBase and FSharpProjectSnapshot.
• setLanguageVersion is replaced by CompilerOptions.ParseLanguageVersion: string -> Result<LanguageVersion, exn>. The --langversion handler reports the returned error, and the snapshot skips it, so the validation exists in one place. The compiler's behavior is unchanged.

[github-actions]

✅ Release notes checked

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✅ Found changes and release notes in following paths:

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Change path	Release notes path	Description
`src/Compiler`	docs/release-notes/.FSharp.Compiler.Service/11.0.200.md	No current pull request URL (#20874) found, please consider adding it