Add fake-depends

**Describe the feature request**

`fake-depends` is a field like `build-depends` which would constraint solver, but otherwise do nothing.

It's sometimes (rarely, but nevertheless) needed to add a constraint, but the dependency is not (at least directly) used anywhere. It would be great if `.cabal` format had a way to explicitly specify that.

One (bad) example is to use `fake-depends: QuickCheck` with `build-depends: tasty-quickcheck`. You can import everything through `tasty-quickcheck` re-exports, but you may need to constraint underlying `QuickCheck`. Arguably `tasty-quickcheck` shouldn't re-export anything, or at least properly version own (re)exports. But here we are.

See `export-depends` in #11052 for another semantically more precise dependency specification field.