Generate CI filter for files included in oxc_ast_codegen

[rzvxa]

Generate what files are watched, It is currently manually written here:

oxc/.github/workflows/ci.yml

Lines 277 to 284 in 82e2f6b

	filters: |
	src:
	- 'crates/oxc_ast/src/ast/*' # single star is intentional
	- 'crates/oxc_ast/src/generated/**' # to potentially cause CI error if generated files are edited manually
	- 'crates/oxc_syntax/src/number.rs'
	- 'crates/oxc_syntax/src/operator.rs'
	- 'tasks/ast_codegen/src/**'

[overlookmotel]

Can we just simplify it to:

filters: | 
  src: 
    - 'crates/oxc_ast/src/**'
    - 'crates/oxc_syntax/src/**'
    - 'crates/oxc_span/src/**'
    - 'tasks/ast_codegen/src/**' 

I know that casts the net a bit wider than it needs to, but:

1. It's foolproof.
2. These crates don't get that much churn (compared to e.g. oxc_linter, oxc_transformer), so job still wouldn't run on 95% of PRs.
3. Somehow generating a ci.yml file feels like overkill.

[rzvxa]

If I'm not mistaken filter can be its own file, So we only generate a simple .github/ast_codegen_filter.yml.
https://github.com/dorny/paths-filter?tab=readme-ov-file#advanced-options
It shouldn't be anything above a few lines of generator code(we just concat string instead of serializing an actual yaml).

A simple generator not only makes sure that all of our current paths are being watched but it would also add new paths to the list as we extend upon it. That's why I felt it would be a good way to set it up and just forget about it.

[overlookmotel]

Ah OK. If it's that easy then, yes, seems like a good idea.

[rzvxa]

Ah OK. If it's that easy then, yes, seems like a good idea.

I'm optimistic that it is quite trivial, I hope time doesn't prove me wrong😆

[overlookmotel]

Implemented in #4737.