Remove hie-compat

While removing references to GHC 9.4, I realized that some parts of HLS are
referring to even older versions of GHC.

For example, `hie-compat` is a compatibility library backporting support of
Haskell IDE Engine (HIE) features to older versions of GHC. Since GHC 9.2,
`hie-compat` only re-exported definitions already present in the `ghc` library,
and so, is essentially obsolete.

FYI: We still have `hie-compat` in the dependency graph, because some
libraries (e.g., `hiedb`) are using it.

Author: dschrempf

CODEOWNERS

@@ -4,7 +4,6 @@
 /hls-graph @wz1000
 /hls-plugin-api @michaelpj @fendor
 /hls-test-utils @fendor
-/hie-compat @wz1000
 
 # HLS main
 /src @fendor

RELEASING.md

@@ -9,7 +9,6 @@
 - [ ] bump package versions in all `*.cabal` files (same version as hls)
   - HLS uses lockstep versioning. The core packages and all plugins use the same version number, and only support exactly this version.
     - Exceptions:
-      - `hie-compat` requires no automatic version bump.
       - `shake-bench` is an internal testing tool, not exposed to the outside world. Thus, no version bump required for releases.
   - For updating cabal files, the following script can be used:
     - ```sh

cabal.project

@@ -1,6 +1,5 @@
 packages:
          ./
-         ./hie-compat
          ./shake-bench
          ./hls-graph
          ./ghcide

docs/contributing/contributing.md

@@ -197,7 +197,6 @@ pre-commit install
 #### Why are some components excluded from automatic formatting?
 
 - `test/testdata` and `test/data` are excluded because we want to test formatting plugins.
-- `hie-compat` is excluded because we want to keep its code as close to GHC as possible.
 
 ## Plugin tutorial