Added integration for ghcide

[mpscholten]

This requires that the project nix config in Config/nix/nixpkgs.nix is updated:

-  nixPkgsRev = "da7ddd822e32aeebea00e97ab5aeca9758250a40";
-  nixPkgsSha256 = "0zbxbk4m72psbvd5p4qprcpiadndq1j2v517synijwp2vxc7cnv6";
+  nixPkgsRev = "07e5844fdf6fe99f41229d7392ce81cfe191bcfc";
+  nixPkgsSha256 = "0p2z6jidm4rlp2yjfl553q234swj1vxl8z0z8ra1hm61lfrlcmb9";

Also update your projects default.nix to point to this branch:

- let
-     ihp = builtins.fetchGit {
-         url = "https://github.com/digitallyinduced/ihp.git";
-         rev = "c4d2815f064c055cd957389a4df5eab25294dba3";
-     };
+ let
+     ihp = builtins.fetchGit {
+         url = "https://github.com/digitallyinduced/ihp.git";
+         rev = "7323d4e5d149d1c1cb4e2798d50cb389e0e12728";
+         ref = "*";
+     };

After that run the following commands:

make -B .envrc # This might take ages to build, like 2 hours
make -B build/ihp-lib
make hie.yaml # needs to be called to create the required config file for hls

Then try to run this:

haskell-language-server

This might take a few seconds, at the end it should say something like Completed (123 files worked, 0 files failed).
When that works, you can use haskell language server from your editor.

When you're doing development on the IHP framework itself and have a locally checked out IHP directory this will fail. Please remove the IHP directory in that case.

Fixes #190