`<pkg-name>.cabal.up` for the glob wary

I'm wary of using any glob-like features in the `.cabal` file (and project file). I want reproducible builds and being explicit helps get us there. I don't want to depend on whatever state my file system is in. Globs don't tell me I'm including junk files or am missing essential files that were not checked in to source control.

Could we take all the globbing features and put them in upstream file from which we then generate a `.cabal` file with globs expanded?

`.cabal.up` -> `.cabal`

> EDIT: note the fact that hpack "works" is because there is clear stage separation. package.yaml is compiled to pkgname.cabal, and pkgname.cabal is used as input to actual build tooling. Blurring the boundary, requiring to .cabal files to be interpreted before further consumption it tricky.
https://github.com/haskell/cabal/issues/5343#issuecomment-521590517