Improve consistency of addons in this org for maintenance

There are a lot of times when I struggle to update or release one of these addons (in the org) because they're all using different configurations.

I'd like to propose that we adopt these standards:

- The primary branch of all repos is `main`
- All packages use `pnpm`
- All packages use `release-plan` (setup instructions here: https://github.com/mansona/create-release-plan-setup)
- ensure each repo has a consistent github ci workflow file
- ensure each repo is using `ember-try`
- use dependabot, use consistent config

For settings:

- update settings so a PR is required
- branches should be deleted after merge
- we'll add a consistent social preview image to each repo

If an addon should be archived:

- file an issue on that repo and let us know in the Discord channel

Did I forget anything?

cc @adopted-ember-addons/admin
```[tasklist]
### Tasks
- [ ] Create template maintanance project
- [ ] Update documentation for this org
- [ ] Add project to each repo in org
```