Add -rpath flag to GHC

Currently, GHC has special logic to handle runtime paths of dynamically linked libraries, however, clients like cabal, cannot benefit from it because the only way to specify rpaths is by passing linker flags directly with -optl-Wl,-rpath ....

We should introduce an -rpath flag that allows clients to specify rpaths to search for dyn libs at runtime which GHC can handle as it does runtime path dependencies determined internally.

This would enable a better solution for tickets like https://github.com/haskell/cabal/issues/7339