GHC needs to distribute .hie files for base libraries

.hie files need to be distributed as part of the release process so that projects using .hie files work with the base libraries.

For example, go-to definition should work for functions defined in the base libraries as well as userland.

The best way to do this might be to distribute a separate tarball which just contains the .hie files which can be downloaded and installed separately to the usual bindists. Another option is to include the .hie files in the bindists, just like how we do for other documentation.

I made a MR !1337 (merged) towards this direction in the expectation of some refinement.