Work around quoting issues on Windows

[gdeest]

Here is the upstream ticket:

bazelbuild/bazel#7122

Potential strategies include:

• Adding dummy spaces to trigger proper quoting.
• Passing command-line arguments via params_file or similar (if those are still needed).

[gdeest]

I got this to work in the gd-win-quoting branch (for GHC invocations only) by dumping arguments into files. For reasons related to the following ticket:

bazelbuild/bazel#6230

I had to make a compromise in the run_ghc function: we can no longer pass multiple Args object as a list, but only a single one. Otherwise, we would have had to create as many params files as Args object, and it would have become a real mess. That is not an issue in my view, as we never used it anyway.

I have confirmed that we can still compile simple binaries on Windows (with a few minor tweaks that will be contributed in a later PR).

However, for reasons beyond my comprehension, it fails on CI for both Linux and Darwin, with Bazel complaining of multiple file declarations ­— while it works perfectly for both @nmattia and I locally, using the same nix-shell and commands as CI. @nmattia is thus gonna pick it up from here to investigate.