Fix for missing parse diagnostics in TransparentCompiler.ParseAndCheckProject

[Martin521]

Description

Fixes #18371.

TransparentCompiler.ParseAndCheckProject does not return any parse errors (while the BackgroundCompiler counterpart does).

This PR fixes this and adds a test.

[github-actions]

❗ Release notes required

---

✅ Found changes and release notes in following paths:

Change path	Release notes path	Description
src/Compiler	docs/release-notes/.FSharp.Compiler.Service/9.0.300.md

[majocha]

Old IncrementalBuilder just appended parse errors here:

fsharp/src/Compiler/Service/IncrementalBuild.fs

Line 279 in 70171b7

let newErrors = Array.append parseErrors (capturingDiagnosticsLogger.Diagnostics |> List.toArray)

I'm not sure how parse errors are handled by Transparent Compiler. They do surface correctly in the IDE, but the code path of this test goes through ComputeParseAndCheckProject:

fsharp/src/Compiler/Service/TransparentCompiler.fs

Line 1910 in 70171b7

let ComputeParseAndCheckProject (projectSnapshot: ProjectSnapshot) =

and it looks like it ignores parse errors (?)

[Martin521]

and it looks like it ignores parse errors (?)

Yes. The parse error is still correctly returned here

fsharp/src/Compiler/Service/TransparentCompiler.fs

Line 1204 in 70171b7

return FSharpParsedFile(fileName, inputHash, sourceText, input, diagnosticsLogger.GetDiagnostics())

but doesn't make it to the project results.

[psfinaki]

Thank you Martin!