This is a follow-on to #17040. The real benefit of #17040 was ensuring
that the ftplugin FileType autocommand was defined first and thus always
fired first. A side effect of the implementation in #17040 was that
setting variables that modified the state of filetype detection (such as
g:did_load_filetypes or g:do_filetype_lua) could no longer be set in the
user's init file. Filetype detection can also no longer be prevented
from loading by using `:filetype off`.
This PR addresses both of those side effects by unconditionally sourcing
ftplugin.vim and indent.vim before the user's init file (which ensures
that these autocommands run first) and sourcing filetype.vim *after* the
user's init file (thus allowing it to be blocked or modified).
de6f9233ee
