System.Runtime.Metadata IL reader

[vzarytovskii]

Description

New IL reader which uses S.R.M, which is faster and more correct. Continuing on top of Will's(@TIHan) work.

Checklist

• [ ] Performance tests (not CI-based, but synthetic ones).
• [ ] Added a compiler switch (off-by-default) which would select old or new reader
• [ ] Test cases added (separate CI leg which will be using --test: flag (see below)
• [ ] --test:* flag which will run both readers and deep-compare their results
• [ ] CI step which will be using said --test flag
• [ ] Release notes entry updated

[vzarytovskii]

Oh well, this didn't go well:

error FS0193: The module/namespace 'RuntimeHelpers' from compilation unit 'FSharp.Core' did not contain the val 'ValLinkagePartialKey(EnumerateTryWith)'

when compiling self

[github-actions[bot]]

:heavy_exclamation_mark: Release notes required

@vzarytovskii,

[!CAUTION] No release notes found for the changed paths (see table below).

Please make sure to add an entry with an informative description of the change as well as link to this pull request, issue and language suggestion if applicable. Release notes for this repository are based on Keep A Changelog format.

The following format is recommended for this repository:

* <Informative description>. ([PR #XXXXX](https://github.com/dotnet/fsharp/pull/XXXXX))

See examples in the files, listed in the table below or in th full documentation at https://fsharp.github.io/fsharp-compiler-docs/release-notes/About.html.

If you believe that release notes are not necessary for this PR, please add NO_RELEASE_NOTES label to the pull request.

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Change path	Release notes path	Description
src/Compiler	docs/release-notes/.FSharp.Compiler.Service/8.0.400.md	No release notes found or release notes format is not correct

[T-Gro]

We agreed with Vlad to close this. Such change would be too dangerous.