Haskell-ide-engine: Test install.hs in CI

[nponeccop]

Currently CI uses a hardcoded sequence of steps. Does it make sense to test a few install.hs targets to be sure that install.hs isn't broken? Note that caching may potentially suffer.
Does it make sense to add some CI-specific targets to install.hs?

[bubba]

I have a branch that tried to add some tests, its pretty stale now though: https://github.com/bubba/haskell-ide-engine/tree/shakefile-ci

[samuelpilz]

My New proposal #1221 will enable unit testing for the install.hs

[jneira]

azure ci is already building stack install.hs help, maybe more goals are needed

[fendor]

More goals and sanity check that the installed binary actually works.