Problem:
The previous fix in #34314 relies on copying the tree in `tree_root` to
ensure the `TSNode`'s tree cannot be mutated. But that causes the
problem where two calls to `tree_root` return nodes from different
copies of a tree, which do not compare as equal. This has broken at
least one plugin.
Solution:
Make all `TSTree`s on the Lua side always immutable, avoiding the need
to copy the tree in `tree_root`, and make the only mutation point,
`tree_edit`, copy the tree instead.
(cherry picked from commit 168bf0024e)
**Problem:** The documentation for `TSNode` and `TSTree` methods is
incomplete from the LSP perspective. This is because they are written
directly to the vimdoc, rather than in Lua and generated to vimdoc.
**Solution:** Migrate the docs to Lua and generate them into the vimdoc.
This requires breaking up the `treesitter/_meta.lua` file into a
directory with a few different modules.
This commit also makes the vimdoc generator slightly more robust with
regard to sections that have multiple help tags (e.g. `*one* *two*`)
