ci: Reduce file size of cabal and stack based builds

By passing -split-sections to all dependencies, GHC will link only the
modules we actually use and not the full package for each dependency.
This does neither work on MacOS nor Windows, thus we don't do it for
stack right now.

Stripping unused symbols in CI will further decrease the size of those files.

cabal.project.non-nix

@@ -4,6 +4,9 @@
 
 packages: .
 
+package *
+  ghc-options: -split-sections
+
 -- Example of depending on a forked repository (the same dependency
 -- would be mentioned in nix/overlays/haskell-packages.nix and
 -- stack.yaml, and should refer to a main branch commit of the