Use VS Code's built-in `ignore` language ID instead of the custom `gitignore` language ID

[NaufalK25]

Hi,

This extension currently uses the custom gitignore language ID. Since VS Code now includes a built-in ignore language identifier, would it make sense to migrate to ignore?

Using the built-in ID could improve interoperability with other extensions and tools that already target ignore.

Reference:

VS Code language identifiers: https://code.visualstudio.com/docs/languages/identifiers#_known-language-identifiers

My assumption is that gitignore was introduced before VS Code provided the built-in ignore language ID, so this may simply be a legacy choice.

Thanks!