[Stable] Add tests for export conditions

[NullVoxPopuli]

I didn't have any failures in

• Add test for library export coditions #2097
  so I copied the tests to the stable branch.

These pass as well -- so this means that if we were to use glimmer-vm's real packages, the correct build would appropriately be selected.

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I'm trying to figure out why we're shipping the Dev version of the VM in production app builds, and this PR is exploring if we're losing export-condition compatibility somewhere.

See also:

• NVP's Quest Issue for Investigating Performance glimmerjs/glimmer-vm#1605
• Rendering performance regression between 0.84.3 and 0.85.1? glimmerjs/glimmer-vm#1590
• [Bug] vendor.js grows by 52 KB in production minified build in 5.6.0 compared to 5.5.0 emberjs/ember.js#20628

Of note, where I've been testing this is old embroider/webpack, so it's possible that, by using vite, all our problems will go away.

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From Ed in Discord:

apps don't even have these [glimmer-vm] packages in their dependency graph

So, the my whole hypothesis about using glimmer-vm's export conditions is out the window.
Idk if it makes sense to keep the tests though.