Add assets for WordPress.org deployment via GitHub Actions

[jeffpaul]

Is your enhancement related to a problem? Please describe.
As originally suggested in 10up/plugin-scaffold#100, we might want to consider adding the necessary files to deploy plugins to WP.org. Before I dig deeper into submitting a PR here, is that something that would be desired since this is mostly (only?) useful for publicly released plugins?

Describe the solution you'd like
Likely mimicking most of 10up/plugin-scaffold#104 here in https://github.com/10up/wp-scaffold.

Designs

Describe alternatives you've considered

Additional context
This sort of example boilerplate plugin info has been requested here as well: 10up/action-wordpress-plugin-deploy#11.