* inject language based on file extension
Nodes can now be captured with "injection.filename". If this capture
contains a valid file extension known to Helix, then the content will
be highlighted as that language.
* inject language by shebang
Nodes can now be captured with "injection.shebang". If this capture
contains a valid shebang line known to Helix, then the content will
be highlighted as the language the shebang calls for.
* add documentation for language injection
* nix: fix highlights
The `@` is now highlighted properly on either side of the function arg.
Also, extending the phases with `buildPhase = prev.buildPhase + ''''`
is now highlighted properly.
Fix highlighting of `''$` style escapes (requires tree-sitter-nix bump)
Fix `inherit` highlighting.
* simplify injection_for_match
Split out injection pair logic into its own method to make the overall
flow easier to follow.
Also transform the top-level function into a method on a
HighlightConfiguration.
* markdown: add shebang injection query
By simply placing a comment with the name of the desired language just
before a multi-line string, that language will be injected.
Also, common functions and attributes which are expected to be shell
code are automatically injected.
