Deno lint for 'custom' files

[EtienneBruines]

Description

Allow linting any file type / extension.

Use case

• Allow writing custom lint plugins, for example to lint .yaml files containing i18n entries. Currently, only typescript files are lintable.

[marvinhagemeister]

Allowing any file type extension might be difficult because at the end of the day there needs to be some form of AST that's passed to the linter. Adding support for other languages is mostly about adding more parsers to deno lint. The plugin system is built in a way that it's unaware of what language it's linting, so that part doesn't need to be touched when supporting new languages.

[petamoriken]

As with ESLint, it might be good to support JSON and Markdown first.
https://eslint.org/blog/2024/10/eslint-json-markdown-support/