Migrate fs-api and fs-sim packages to the fs-sim repo.

[jorisdral]

Description

Part of #4082.

This PR removes the fs-api and fs-sim packages from the ouroboros-network repository. The code is added to the fs-sim repository in this PR: input-output-hk/fs-sim#2.

For now, we will have a source-repository-package entry in the cabal.project file, which can be removed once both fs-sim and fs-api are published to the CHaP.

Checklist

• Branch
  • Commit sequence broadly makes sense
  • Commits have useful messages
  • The documentation has been properly updated
  • New tests are added if needed and existing tests are updated
  • Any changes affecting Consensus packages must have an entry in the appropriate changelog.d directory created using scriv. If in doubt, see the Consensus release process.
  • Any changes in the Consensus API (every exposed function, type or module) that has changed its name, has been deleted, has been moved, or altered in some other significant way must leave behind a DEPRECATED warning that notifies downstream consumers. If deprecating a whole module, remember to add it to ./scripts/ci/check-stylish.sh as otherwise stylish-haskell would un-deprecate it.
  • If this branch changes Network and has any consequences for downstream repositories or end users, said changes must be documented in interface-CHANGELOG.md
  • If serialization changes, user-facing consequences (e.g. replay from genesis) are confirmed to be intentional.
• Pull Request
  • Self-reviewed the diff
  • Useful pull request description at least containing the following information:
    • What does this PR change?
    • Why these changes were needed?
    • How does this affect downstream repositories and/or end-users?
    • Which ticket does this PR close (if any)? If it does, is it linked?
  • Reviewer requested

[jorisdral]

bors r+

[iohk-bors]

Build succeeded:

• ci
• build (9.2.5, windows-latest)
• Check git dependencies
• check-cabal-files
• ci (x86_64-linux)
• Consensus changelog sanity check