feat: add new build-config package

[runspired]

playing around with a new package to centralize configuration and allow us to ship v2 addons. currently the approach won't work because package presence requires either addon-main's to report into global config they are present (which then introduces timing bugs) or for configuration to somehow run from the perspective of the consuming addons.

This removes all HAS_PACKAGE checks which while something we wanted to do may prematurely cause us a ton of grief due to how poorly embroider/macros works with pnpm hardlinks

TODO (not necessarily in this PR)

• [x] move feature list into build-config
• [x] move deprecation list into build-config
• [x] move debugging list into build-config
• [x] convert all addons to v2
• [x] convert all packages to eslint flat config
• [x] convert all tests to eslint flat config
• [x] get blueprints working again
• [x] get addon-test-support working again
• [x] fixup app re-exports
• [x] fix usage of private types
• [x] fix test-apps
• [x] eliminate private-build-infra addon
• [x] dont use assert from @ember/debug

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• [ ] remove exports stripping from publish script
• [ ] change to using extensions in addon files
• [ ] rollup types
• [ ] prevent breaking change by having ember-data addon always set global config