runtime(vim): Improve keymap file highlighting (vim/vim#13550)
- Match :loadkeymap to EOF as a region and contain only allowed items.
- Add highlighting for <Char- notation.
- add basic syntax highlighting tests
69866449dd
N/A patches:
vim-patch:35928ee8f80ea721e92bb856c8ecde2cced46bb9
vim-patch:b5352931b354eb67eb7d223cc09c98dcf1b547b6
Co-authored-by: dkearns <dougkearns@gmail.com>