runtime(i3config/swayconfig): update syntax scripts
modifications with the goals of:
- simplifying structure by using group `cluster`s
- improving visual highlighting responsiveness by using `nextgroup`
- improving recursive wm-msg command highlighting
- separating command variants meant for runtime and for config only
closes: vim/vim#14544dd83b63eb5
Update runtime files
10e8ff9b26
Also:
- fix a missing `<` in builtin.txt.
- edit `:function` `{name}` wording to match the change made for the docs above
by Justin in #10619.
- link to `*vimrc*` rather than `*init.vim*` in repeat.txt change (as `init.lua`
may also be used).
Co-authored-by: Bram Moolenaar <Bram@vim.org>