Move the linters to run on BufReadPost instead of BufEnter. This was
running the linters whenever a buffer opened, when jumping around
quickly with <CTRL-i> and <CTRL-o> this would cause the linters to run a
lot when there were not needed. Now were are only running them once when
the buffer is read from disk.
Adds a custom function that will add cspell to all of the filetypes.
This will then only run `try_lint` once to improve the performance. Now
neoformat has gone fully async. When calling `try_lint` one after the
other, the first processes were getting canceled.