Fix for GET with projections

[bterlson]

Tentative fix #812, as I ran out of time to fix it properly. The root cause of this issue seems to be that getEffectiveType doesn't respect projections. The fix I think we should do is to update gET to consult the program's current projection and map the type there. I think @nguerrera should comment on a proper fix, so this is a minimally invasive and somewhat garbage-y wrapper around gET that projects any return value.

[azure-pipelines]

You can try these changes at https://cadlplayground.z22.web.core.windows.net/prs/819/

[daviwil]

I think this fix is headed in the right direction because it does fix the issue I reported in #812 (at least for the "Language Authoring" spec, but after testing it a with the Azure.Core versioning PR (https://github.com/Azure/cadl-azure/pull/1754), I see the following error while running the cadl-samples/data-plane/formrecognizer spec:

Cadl compiler v0.33.0

Internal compiler error!
File issue at https://github.com/microsoft/cadl

Error: Namespace FormRecognizer should have already been projected.
    at compilerAssert (file:///home/daviwil/Projects/Code/cadl/versioning/core/packages/compiler/core/diagnostics.ts:293:9)
    at projectType (file:///home/daviwil/Projects/Code/cadl/versioning/core/packages/compiler/core/projector.ts:100:9)
    at projectedNamespaceScope (file:///home/daviwil/Projects/Code/cadl/versioning/core/packages/compiler/core/projector.ts:510:12)
    at shallowClone (file:///home/daviwil/Projects/Code/cadl/versioning/core/packages/compiler/core/projector.ts:555:30)
    at projectModel (file:///home/daviwil/Projects/Code/cadl/versioning/core/packages/compiler/core/projector.ts:250:28)
    at Object.projectType (file:///home/daviwil/Projects/Code/cadl/versioning/core/packages/compiler/core/projector.ts:107:21)
    at Object.getProjectedEffectiveModelType [as getEffectiveModelType] (file:///home/daviwil/Projects/Code/cadl/versioning/core/packages/compiler/core/checker.ts:4122:52)
    at getEffectiveSchemaType (file:///home/daviwil/Projects/Code/cadl/versioning/packages/cadl-autorest/src/openapi.ts:678:41)
    at getSchemaOrRef (file:///home/daviwil/Projects/Code/cadl/versioning/packages/cadl-autorest/src/openapi.ts:631:12)
    at getSchemaForModel (file:///home/daviwil/Projects/Code/cadl/versioning/packages/cadl-autorest/src/openapi.ts:1163:26)

It seems like we might need to investigate the source of this error before we can merge this PR. The weird thing is that I can't really even tell by looking at the Form Recognizer spec what might be triggering this.

We're in luck, though: this test is failing with the same error so we might be able to clamp down using that test and figure out why the error occurs.

[nguerrera]

I think @nguerrera should comment on a proper fix, so this is a minimally invasive and somewhat garbage-y wrapper around gET that projects any return value.

I missed this while I was away and am hitting something related now. It seems suspect that getEffectiveModelType is finding unprojected types for a projected type. It appears that we are not fixing up parent .model and .sourceProperty when projecting. However, so far when I do that more things break :(

[nguerrera]

#1069 tracks this now