WIP: Add local template option

[cprecioso]

Description

As part of #3073, I'd like to generate a project from a locally-downloaded version of OpenSaaS.

I added a new kind of template and a hidden command wasp new:custom to handle this case.

Connections

• Working towards open-saas development version is out of sync with wasp development version #3073
• On top of all these refactorsm -- split into their own PRs for ease of review:
  • Refactor StarterTemplate data structure #3340
  • Rename LocalStarterTemplate to BundledStarterTemplate #3341
  • Refactor ProjectDescription #3342
  • Add dir path argument parser #3343
  • Extract file path argument parser #3344
  • Split StarterTemplates to AvailableTemplates #3345
  • Remove unused GhRepo starter type #3346

Type of change

• 🔧 Just code/docs improvement
• 🐞 Bug fix
• 🚀 New/improved feature
• 💥 Breaking change

Checklist

• I tested my change in a Wasp app to verify that it works as intended.

• 🧪 Tests:

  • I added unit tests for my change.
  • (if you fixed a bug) I added a regression test for the bug I fixed.
  • (if you added/updated a feature) I added/updated e2e tests at examples/kitchen-sink/e2e-tests.
  • (if you added/updated a feature) I updated the starter templates at waspc/data/Cli/templates, as needed.

• 📜 Documentation:

  • (if you added/updated a feature) I added/updated the documentation in web/docs/.

• 🆕 Changelog: (if change is more than just code/docs improvement)

  • I updated waspc/ChangeLog.md with a user-friendly description of the change.
  • (if you did a breaking change) I added a step to the current migration guide at web/docs/migration-guides/.
  • I bumped the version in waspc/waspc.cabal to reflect the changes I introduced.