feat: hosted actions

[jonthegeek]

Summary

As a package developer, I'd like the core of the copilot-setup-steps.yml workflow to be "hosted" in the pkgskills repo, so that I don't have think about basic updates.

Details

I moved composable actions to a new api2r/actions repo.

Update the copilot-setup-steps.yml action (both in .github/workflows/copilot-setup-steps.yml and inst/templates/workflows/copilot-setup-steps.yml) to reference uses: api2r/actions/install@v1 rather than uses: ./.github/workflows/install. Delete .github/workflows/install/action.yml and inst/templates/workflows/install/action.yml.

Update use_github_copilot() (in R/use_github_copilot.R) and its tests to only install inst/templates/workflows/copilot-setup-steps.yml. The install piece no longer needs to be installed to the package repository.