Breaking type changes in 6.4

[ef4]

Between ember 6.3 and 6.4-beta, a bunch of @glimmer/* packages made breaking changes to how they publish their types. Those types are incorporated as part of Ember's public API.

An example is @glimmer/manager 0.92.4 -> 0.94.8 which dropped the types key in package.json in favor of exports.*.types. This forces apps to change their moduleResolution setting, which they cannot always do because other dependencies may not yet work under that setting.

This is going to cause real apps to be blocked from upgrading. I don't think it's reasonable to force a global config change in a minor.

I think we should either

1. patch the glimmer packages to bring back type compatibility,
2. or work on rolling their types into ember-source and dropping them from ember-source's dependencies instead of incorporating them by reference.

Option 2 is consistent with our vision of integrating the glimmer-vm repo into this repo and making all the internal glimmer packages an entirely internal concern. That gives us the maximal freedom to refactor them. It's also consistent with the fact that their implementation is already rolled into ember-source. It's Not Good that their implementation comes from ember-source but their types come from the real packages.