Replace haskell-src-exts

[brandonchinn178]

It looks like haskell-src-exts is on life support, with ghc-lib-parser the recommended alternative.

My specific issue is that parseExp doesn't parse OverloadedRecordDot correctly, so I can't do ${foo.bar} in the sql quasiquoter

[mzabani]

Given I'm a complete novice to GHC's AST and even template haskell, I took a look at using ghc-lib-parser. After failing to find good docs and even running into a lack of haddocks on Hackage, I asked Claude to write something.

Now, I don't like using Claude very much because it bit me a few times in the past, so I've been avoiding it for all but the more trivial tasks. But it produced something I was able to read and then iterate on so I can learn a little bit about all of this. I pushed it to #39 if you want to take a look.

I'm writing this to say that I'll let that PR sit there for a couple of weeks. While I was able to make a few adjustments to the code written by Claude, I'm reading the code line by line so I'm certain I understand all of it before I merge. Given the lack of docs, this means I'm reading code Notes in ghc-lib-parser, trees that grow, etc., and that will take a few weeks.

Also, I wrote a test that creates a record and accesses its field, all inside #{}, and that fails to compile. I still want to test TypeApplications and whatnot - I'm not sure how much I need to support, and I'm not sure how much haskell-src-exts supports, but I want to test the space of possibilities before merging so I have a better idea what this entails in practice.

That being said, the PR I linked already supports OverloadedRecordDot if you want to try it out.