[Plugin] Support Tree-sitter

[NNBnh]

From Tree-sitter's website:

Tree-sitter is a parser generator tool and an incremental parsing library. It can build a concrete syntax tree for a source file and efficiently update the syntax tree as the source file is edited. Tree-sitter aims to be:

• General enough to parse any programming language.
• Fast enough to parse on every keystroke in a text editor.
• Robust enough to provide useful results even in the presence of syntax errors.
• Dependency-free so that the runtime library (which is written in pure C) can be embedded in any application.

I think this is the most important feature that missing in Pepper.

[vamolessa]

This may be out-of-scope for this project as one of it's goals is to try to not rely on third-party libraries and keep things simple and orthogonal.

That said, it would be cool to be able to support a tree-sitter integration through a plugin
(would still require some work on the plugin system, tho)

[vamolessa]

I've marked this as wontfix since integrating tree-sitter is out-of-scope for this project.
However, it will remain open, at least of a while, in the case someone would like to implement a plugin that does the integration.