Fix polyglot ftdetect as fallback for native vim

[Kache]

Fix polyglot ftdetect as fallback for native vim

Fix ftdetect for ft ext defined only by native vim, e.g.
*.jjdescription, *.http, *.mysql_history, & others

It seems vim-polyglot loads vim-filetype.vim then clobbers it by
"resetting" with au! filetypedetect afterwards, even though
vim-polyglot intends to be a fallback, according to comments in
init.vim

This is evidenced by *.jjdescription, *.http, and .mysql_history,
filetype extensions defined in vim-filetype.vim but not
polyglot-filetype.vim:

vim -c "set filetype?" -c 'sleep 2' -c 'q!' foo.jjdescription
vim -c "set filetype?" -c 'sleep 2' -c 'q!' foo.http
vim -c "set filetype?" -c 'sleep 2' -c 'q!' .mysql_history

Compare:

vim --clean -c "set filetype?" -c 'sleep 2' -c 'q!' foo.jjdescription
vim --clean -c "set filetype?" -c 'sleep 2' -c 'q!' foo.http
vim --clean -c "set filetype?" -c 'sleep 2' -c 'q!' .mysql_history

And:

vim -c "set filetype?" -c 'sleep 2' -c 'q!' foo.py
vim -c "set filetype?" -c 'sleep 2' -c 'q!' foo.bash
vim -c "set filetype?" -c 'sleep 2' -c 'q!' foo.js

Note although vim-polyglot does not define bash.vim nor
javascript.vim, polyglot-filetype.vim does define the *.bash and
*.js extensions, so they "still work"

I'm using vim --version and vim-plug:

VIM - Vi IMproved 9.1 (2024 Jan 02, compiled May 23 2025 00:48:59)
Included patches: 1-948, 950-1230, 1242, 1244

Tried to retain original intent to first load poly-filetype.vim then
vim-filetype.vim on top. Early workarounds:

• disable vim-polyglot ftdetect let g:polyglot_disabled = ['ftdetect']
• init.vim: comment out au! filetypedetect
• init.vim: comment out Load user-defined... and Prevent filetype.vim... paragraphs

Unsure how to test "vim-filetype.vim loads first case", which seems
related to handling nvim and other package managers,
which I haven't done

My print debugging output below, indentations for clarity.

Before:

poly filetype.vim start
  init.vim start
    init.vim did_load_polyglot: false
    init.vim runtime! filetype.vim
      poly filetype.vim start
	init.vim init() no-op
      poly filetype.vim end
      vim filetype.vim start
	init.vim init() no-op
      vim filetype.vim end
    init.vim init() no-op
    init.vim did_load_filetypes: true
  init.vim end
  init.vim init() no-op
poly filetype.vim end
vim filetype.vim start
vim filetype.vim finish early
polyglot.vim start
  init.vim init() no-op
polyglot.vim finish

After:

poly filetype.vim start
  init.vim start
    init.vim did_load_polyglot: false
    init.vim did_load_filetypes: false
  init.vim end
  init.vim init() no-op
poly filetype.vim end
vim filetype.vim start
  init.vim init() no-op
vim filetype.vim end
polyglot.vim start
  init.vim init() no-op
polyglot.vim finish

Related: #706, #758, #756, #871, NoahTheDuke/vim-just#125
Fix: #877, #829, #845, #817

[Kache]

For reference, latest versions:

https://github.com/vim/vim/blob/54cc8201291e6f8860084ce7e7cd5b8069344612/runtime/filetype.vim
https://github.com/sheerun/vim-polyglot/blob/f061eddb7cdcc614c8406847b2bfb53099832a4e/autoload/polyglot/init.vim