Commit 2f97657 added default setup dep
handling to the existing install command code paths, but unfortunately
broke the handling for the new-build code path. It added a call to
addDefaultSetupDependencies into the standardInstallPolicy. That
interfered with the addDefaultSetupDependencies that ProjectPlanning was
already using.

So this patch splits a basicInstallPolicy out of standardInstallPolicy,
where the basicInstallPolicy is all the old stuff, and the
standardInstallPolicy just adds the addDefaultSetupDependencies that the
install/fetch/freeze commands need. So then ProjectPlanning uses just
the basicInstallPolicy.

The 2f97657 commit also added a new and simpler method to determine if a
package has had default setup deps added. Previously ProjectPlanning had
to use a rather complex method to remember this information. So this
patch removes all that and makes use of the new method.

To stop this breaking in future the next patch adds integration tests to
cover custom setup script handling.

This fixed issue haskell#3394.

Covers 3 of the 4 possible cases:
1. explicit custom setup deps
2. custom setup with implicit/default deps
4. non-custom setup using the internal cabal lib version

case 3 is a non-custom setup but where we're forced to use an external
cabal lib version. This case is hard to test since it only happens when
it's a newer (not older) Cabal lib version that the package requires,
e.g. a .cabal file that specifies cabal-version: >= 2.0.

Also, add a --with-ghc option to the integration test suite, which lets us
more easily test with different ghc versions.

Also, don't use parallel builds in any of the integration tests, as the
self-exec method will not work, and some tests need to install deps for
some ghc versions.