Improve the Tree-Sitter inspector

[narnaud]

More discussion, quite some changes as we did a 180° turn.

• we keep the inspector as a second window
• we add a button for the code views to open the inspector (for better discoverability)
• improvement on the query editor
  • better syntax highlighting (use scm for that)
  • load/save queries (using scm extension for that)
  • wiggle on error line

[narnaud]

Here is a proposal:

• Create a CodeView that could be split, with the code on the left and the TreeSitter tree on the right (one button click will show/hide it), something like Neovim TreeSitter
• Add a dock for writing TreeSitter query, that you could save and load (apparently the extension is .scm)

This is completely removing the current dialog, but better integrate TreeSitter into Knut.

[LeonMatthesKDAB]

Sounds good overall. The inspector could definitely use some love. It's been working fine but it's UX isn't great right now.

Side Note: .scm stands for scheme. Tree-sitter doesn't actually use scheme syntax, but it's close enough that highlighting, etc. should work fine.
We should check whether KSyntaxHighlighter has a lisp/scheme highlighter, which could be good enough.

[narnaud]

It does, and it's already in Knut... we should definitely try that before doing our own...