Migrate to v2 addon

[simonihmig]

To Do:

• Update docs
• Add migration guide
• Test classic build + ember-auto-import (Blocked on Feature: allow ember-auto-import to own parts of of the app embroider-build/ember-auto-import#565)
• Investigate composability of webpack loaders
• Extract blurhash support into its own package? (Would allow to conditionally (macroCondition) include support code in core component)
• Update to latest v2 addon blueprint
• Figure out how to make TS happy about image imports (+ add to docs)
• Extract image CDN helpers to own packages
• Figure out final place to put addon config in
• webpack loader tests (including different sources of config)
• keep main addon as ember-responsive-image
• Setup Renovate for v2 branch
• align to latest v2 blueprint

[simonihmig]

For anyone looking at this, I have closed the PR as it had merge conflicts with master, and given how far the two branches have diverged, there isn't really a good reason to merge them. I'll keep this one as the "next" branch, until we are ready to release this as a major version, and rename it to master (or main probably)