Rich markdown rendering/highlighting for docs on hover

[VarLad]

Currently the text printed within hover docs looks quite raw.
It would be nice if we could have rich rendering instead.
An interesting project which makes this possible might be https://github.com/Canop/termimad

[neurocyte]

https://github.com/JacobCrabill/zigdown is written in zig and uses tree-sitter. Probably a better match for flow than termimad.
An alternative would probably be to write a simple markdown renderer using the tree-sitter ast.

Either way it should use colors from the current flow theme.

[neurocyte]

The implementation of this feature is likely possible entirely in src/tui/info_view.zig. That means it could be a really nice "first issue" for a new contributer.