Initial Investigation adding SMT Dependencies to Plutus Libraries

Running tests

1. nix develop
2. cd plutus-tx
3. cabal run liquid-test

Note that these tests don't test the actual modules in the library themselves but instead run some basic smt tests. Proper library testing is left to future work.

Branches

The main branch adds support for liquid haskell for the plutus-tx library.

The sbv-test branch adds support for sbv for the plutus-tx library.