vim: update config, support nvim, del editorconfig

vim: update config, support nvim, del editorconfig

- many config options were not being applied globally, since they were not
  global options themselves. they have been made global using autocommands.
- nvim did not work properly as some options are not compatible/not necessary
  with it.
- editorconfig is built-in as of vim 9, so the repo is no longer necessary. it
  has been removed, and the editorconfig optional package loaded when vim
  starts.