Fix #6377 Drop support of Cabal < 2.2

[mpilgrem]

• Any changes that could be relevant to users have been recorded in ChangeLog.md.
• The documentation has been updated, if necessary

Please also shortly describe how you tested your change. Bonus points for added tests! Relying on CI.

[mpilgrem]

@theobat, I think this implements what we have discussed. However, before I put it through, may I double-check that you still think that dropping support for Cabal < 2.2 will make it easier for you to make the other changes that you have in mind?

[theobat]

@mpilgrem, it's not that it'll make the planned changes easier, it's that we can't have component based builds for cabal less than 2.2, because the interface* simply didn't exist.
Component based builds are a requirement for several things such as backpack and more parallelism at the action level (parallel per components versus parallel per packages).

And given this requirement, it also makes sense to remove the complexities of these cabal versions.

* Quoting the cabal doc:

In Cabal 2.0, support for a single positional argument was added to runhaskell Setup.hs configure This makes Cabal configure the specific component to be configured. Specified names can be qualified with lib: or exe: in case just a name is ambiguous (as would be the case for a package named p which has a library and an executable named p.)