Enable loading and error substates

[evoactivity]

Closes #18

[NullVoxPopuli]

Tests? <3

[evoactivity]

That was a tricky one to figure out how to test for, I had to manually run setupRouter from the instance.

[evoactivity]

Dasherizing the names always is fine I think. A user would actually create application-loading.gts on disk

[evoactivity]

@NullVoxPopuli any chance you can rerun the failed tests here for me so I can see why they fail.

[evoactivity]

Well that was less illuminating than I was hoping.

[commonjs--resolver] /home/runner/work/ember-strict-application-resolver/ember-strict-application-resolver/node_modules/.pnpm/ember-source@7.1.0_@glimmer+component@2.1.1/node_modules/ember-source/dist/dev/packages/ember-testing/index.js: Cannot find module '/home/runner/work/ember-strict-application-resolver/ember-strict-application-resolver/node_modules/ember-source/dist/prod/packages/dist/ember-template-compiler.js'

I'm not really sure what to do in this situation :/

[NullVoxPopuli]

I'm not really sure what to do in this situation :/

thats this: https://deprecations.emberjs.com/v6.x#toc_using-amd-bundles

the test-apps need updated