vim syntax matching acts in the most weird ways

holy shit this was fucking hard

refactor(*): remove upstream stuff

See merge request !2

https://github.com/dense-analysis/ale/pull/3424

ftdetect: unconditionally set filetype

Closes #1

See merge request !1

According to the [documentation][0], "`setfiletype` will only set
'filetype' if no file type was detected yet."

To always set it, we need to use `set filetype=apkbuild`.

Fixes #1

[0]:https://vimhelp.org/filetype.txt.html#new-filetype