[feature] Plugin system

[Freed-Wu]

Is your enhancement related to a problem? Please describe.

TOML language server tombi support an extension system to process a special TOML files, such as pyproject.toml, Cargo.toml.

Describe the solution you would like

Is it possible yaml-language-server to support extension system to support some special YAML files? such as github action YAML, sublime syntax, ...

Describe alternatives you have considered

Create another language server for some special YAML files. such as actionlint

Additional context

[datho7561]

It might be interesting to do this, but I think it'd make the language server much more complicated and that would be a massive tradeoff. I don't know specifically how we'd build a plugin system for JavaScript (i.e. how do we discover plugins and load their logic?).

I think a lot of the specific YAML file types already have their own language server or their own VS Code extension (though I guess that's less helpful for IDEs that aren't VS Code or its forks). GitHub Actions in particular.

It would be really hard to support Helm and Jinja with a plugin system, since those files have a bunch of their own syntax even though they still have the .yaml extension. We'd need to figure out how to make the parser itself swapable in order to support them.