azure: add windows+cabal job and other improvements

[jneira]

• Separate test suites:
  • To handle specific conditions, make log inspection easier and run them with cabal without -j1
  • unit-test
  • dipatcher-test, plugin-dispatcher-test, wrapper-test
  • functional-test
• Add ghc-8.8.1 to linux and macos jobs (Add azure CI for cabal GHC 8.8.1 #1593)
• Add cache to installhs jobs
• Install ghc's in windows+stack jobs in drive D: to avoid errors about no space in C:
• Change stack_root to D: in windows+stack for the same reason
• Add new job windows+cabal for ghc 8.6.5 and ghc-8.4.4
  • Using chocolatey to download cabal and ghc
  • Separating the store-dir of builds and install to avoid Error building/installing cabal-helper-1.0.0.0 cabal#6483
• Enable installhs job for windows+cabal
• Other minor fixes

[fendor]

LGTM! Great work!

[jneira]

Only left the macos+cabal job but i am gonna take a rest from azure 😄

[jneira]

I have to investigate why windows jobs fail installing the alternate ghc necessary to install liquid. In my repo it works fine: https://dev.azure.com/jneira/haskell-ide-engine/_build/results?buildId=567

But i would merge cause they are already failing for the same reason