Allow to build with cabal

The process to create these files is as follows:

1. Run stack2cabal
2. Disable tests and benchmarks of local packages
   (those specified via source-repository-package...
   this won't be needed with cabal-3.4 anymore, because it won't treat
   them as local anymore)
3. Hackage packages in `packages` in `cardano-1.19.x.yaml` or `extra-deps`
   in `stack.yaml`, which are specified as git repositories might
   have different versions than the stack resolver. `stack2cabal`
   cannot pick these up, so these must be adjusted manually (or deleted) in
   `cabal.project.freeze` (at the time of writing: http-client and persistent).

Rationale:

1. good to support all available tools as options for interested users
2. cabal allows easier managing of package bounds (and testing against
   latest package versions and different GHCs, because it is not
   constrained to stackage)
3. doesn't require nix, which is an additional step to set up and
   maintain and requires significant amount of disk space