Analogous to nodejs's `on('data', …)` interface, here on_key is the "add
listener" interface.

ref 3ccdbc570d85 #12536

BREAKING_CHANGE: vim.register_keystroke_callback() is now an error.

This is a fixup for #14915, which used the above-mentioned call to
restore the behavior of the pre-release version of tree-sitter to
that of 0.19.5. However, this function was introduced after 0.19.5,
breaking distro builds that link against 0.19.5 instead of the tag
specified in neovim's build script.

Now the function should only be called when it is available _and_
needed. Once tree-sitter is bumped to 0.19.6 (when this is released),
this guard can be removed again.

Fixes #14923 (among others)

Upstream tree-sitter raised the number of pending matches for a query cursor
from 32 to 64k in <https://github.com/tree-sitter/tree-sitter/commit/
78010722a49ed6224c773c22b0d25a8c9fbde584>, which severely impacted performance
for some highlighting queries. This uses the `ts_query_cursor_set_match_limit`
function introduced in <https://github.com/tree-sitter/tree-sitter/commit/
cd96552448a6e0d4eb27fc54b27cb5130c4b6f76> to manually set this back to the old
default of 32.

Fixes #14897

When a keymap is set from lua currently verbose message says
it's set from line 1. That's incorrect because we don't really know when
it was set. So until proper :verbose support isn't added for sourceing
lua it shouldn't say where it was set at.

fix(lua): ensure vim.region truncates to buf range

If vim.region receives a large range outside of the current buffer
bounds, it will not check the range ahead of time and loop until neovim
exhausts the system memory.

Fixes #14743

So now :source can run lua files too :)

* feat: Add support for :[ranged]source for lua files

* lua: Add vim.opt

* fixup: cleaning

* fixup: comments

* ty clason

* fixup: comments

* this is the last commit. period.