Baseline parser tests

[nojaf]

This is a first attempt at tackling #13484.

I migrated the existing parser tests (which asserted patterns in the AST) with baseline tests.
These tests will be more interesting to detect regressions early on.

[auduchinok]

@nojaf This is really cool!

Maybe we could move the files into subfolders, mimicking the file structure that was there before:

tests/service/data/SyntaxTree/Type/...
tests/service/data/SyntaxTree/Expression/...
tests/service/data/SyntaxTree/ModuleOrNamespace/...

We'll likely add a lot of these files, so maybe we could have some organization strategy from the start.
Otherwise, we could have this kind of structure in the file names, but I think it'll be much more difficult to maintain when there're many contributors.

[vzarytovskii]

That's great, thanks!

[nojaf]

@auduchinok I took a shortcut for __SOURCE_DIRECTORY__, I think this is ok for now.

[auduchinok]

Is there an easy way to run/debug a specific test? It's going to be crucial when debugging some cases in the parser (e.g. debugging helped me a lot when I worked on the parser in #13352).

It would also be very handy to be able to dump tokens for a specific tests easily: it may really help when changing LexFilter, as in #13089.

@nojaf@vzarytovskii Would it be easy to have separate named tests, similar to what we have here? https://github.com/JetBrains/resharper-fsharp/blob/net231/ReSharper.FSharp/test/src/FSharp.Tests/Parsing/FSharpParserTest.fs

[auduchinok]

Ouch, I'm a bit late 😞

[nojaf]

You can debug each individual file: