Simplified template resolution

[ef4]

This is another extraction from the work in #1357.

It should be able to complete the "stretch goal" described in #1339 by eliminating all real module resolution in our template transform.

I noticed that emberjs/ember.js#19878 got back ported to Ember 3.28, so I don't think we need to keep our workaround for it anymore, and dropping the workaround made this work easier.

Potentially breaking changes to how we up-compile non-strict templates:

• we're getting stricter about letting ambiguous forms like {{thing}} mean {{this.thing}}. Ember itself doesn't support any versions that can do this anymore. Embroider will now error on this when staticComponents or staticHelpers are enabled. If people hit this problem in third-party code, I've added a disambiguate package rule that can be used to manually disambiguate the cases.
• related to the above, if you use forms that are ambiguous between helper and component like {{thing arg=1}}, you can no longer mix and match staticComponents and staticHelpers settings. They either both need to be enabled or both disabled. You can also always switch to unambiguous syntax like <Thing /> or {{ (thing) }}. This way we can always tell for sure whether we're handling an invocation or not, without making it dependent on the outcome of global resolution.
• the components.*.safeToIgnore package rule used to just suppress the error when a component wasn't found. Now it prevents us from even attempting resolution.
• we no longer include a workaround for [Bug] class-based helpers throw weird error in strict mode (getDebugName) emberjs/ember.js#19877, because the fix for that is back ported to 3.28. All our supported Ember versions have a non-breaking ember upgrade they can do to get the fix.