Devops/packaging action

[jasonsiders]

New CI job to facilitate automatically packaging both a Managed and Unlocked package versions on new pushes to main.

To push a specific version number, increment sfdx-project.json's versionNumber property in the push to main. If not, the script will increment the existing version number's patch version (ex., 2.5.1 -> 2.5.2).

The job will sequentially create a managed package version, and an unlocked package version, and then create a release. The release contains the relevant package ids & installation commands, plus github's auto-generated release notes.

If needed, the release.yml action can be dispatched manually, as can individual packaging actions via packaging.yml.

This change also includes the creation of a new packages/ folder structure, which stores sfdx-project.json files for both the unlocked and managed packages. There also needs to be a sfdx-project.json file at the root of the project, to facilitate development. The CI action swaps out the root file for correct packages/ file at runtime.