Convert to V2 Addon

[NullVoxPopuli]

We already require ember-auto-import@v2 so when this PR is complete, it would have been a non-breaking change -- however, I also dropped support / testing for ember-source < 3.28 for some sanity reasons. Previously 3.25 was tested against, but it wasn't until 3.27 that ember-source started shipping regular ESM. The differences are minor, but can surface issues in weird ways -- I mostly don't want to deal old code so.. here we have 3.28 as the minimum version now 🙃

How we got here (in order)

1. Move ember-modifier to dependencies #127
2. Remove @tailwindcss/ui #147
3. Switch to pnpm #148
4. Convert to monorepo #152
5. Move tests to own app #157
6. and now this PR! (Convert to V2 Addon #158)

How do you review something like this? (It's still a big PR)
Points of interest:

• the ci workflow is now generated from the root ci.yml, using: https://github.com/NullVoxPopuli/ember-ci-update
• the rollup.config presently makes all files publicEntrypoints. We'll likely want to shift to gjs/gts and private component/modifier imports to reduce those publicEntrypoints -- because there is def stuff we don't want to be public API as most of this addon is to support the publicEntrypoints

Things to keep in mind

• v2 addons + monorepos simulate real npm package + app consumption as close as possible
• we don't have any sort of deploy preview set up or anything, so you may want to see if the docs app boots up and looks fine
• if all the status checks are green, we should be good to go

[rreckonerr]

@NullVoxPopuli Hi!
Thanks for a great addon! Do you have any plans to make a new release of the addon any time soon?

[tniezurawski]

Great stuff @NullVoxPopuli! (as always). Do you remember what was wrong with this PR? The "CI / Build tests" job was failing but the artifacts are no longer available.

What is the work needed to push it through?

[NullVoxPopuli]

Yeah, i was having an issue with tests using apis that don't exist in the browser that were polyfilled by webpack4