Add support for post qualified import formatting.

[jhmcstanton]

Adds an option to use post qualified module imports.

Related to #284 Resolves #334

Let me know if any more tests or changes are needed.

[jhmcstanton]

Not sure what the issue is with that mac build, classic case of "works on my machine". Not sure that I have access to rerun the build though, can someone with access trigger that for me (or show me how) ?

[akrmn]

This is exactly what I'm looking for right now.

It seems like the build error is the same one I got on #337, @jaspervdj, could we ignore it again for this PR?

[akrmn]

hm, this seems to fail on post qualified explicit imports:

import Data.Aeson qualified as JSON (Value)

gives me:

RealSrcSpan SrcSpanOneLine "./test.hs": parse error on input `qualified'

I'll add a few failing test cases later today

[EncodePanda]

@jhmcstanton would it be much work now to rebase this against main?