Proposal: Move GHC testsuite tests in submodules into GHC

Currently there are a few core libraries which have tests which are run by GHC's testsuite driver. This is inconvenient as changes in these tests require awkward cross-repository changes. Moreover, these tests do little to help correctness as the libraries' upstreams generally don't use GHC's testsuite driver in their own validation pipelines.

I propose that we begin moving the follow sets of tests from their respective repositories into testsuite/tests/libraries/...:

• libraries/process/tests
• libraries/parallel/tests
• libraries/Win32/tests

See also: https://github.com/haskell/process/pull/268