Collapse unions of objects with an inferable discriminator into tagged unions

[jeskew]

Split off from work on #9736, which requires a couple changes that are easier to consider as standalone PRs.

This PR updates the TypeCollapser to handle unions of objects that share a required, string-literal-typed property for which each member of the union has a unique value. (If there are multiple viable discriminators, the TypeCollapser will try to use a property named type or kind, then fall back to the first viable discriminator name in an ordinal alphabetic sort.)

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 6560930679)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 6560930679

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 6560930679"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 6560930679

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 6560930679"

[github-actions]

Test Results

     132 files  ±  0       132 suites  ±0   4h 2m 33s ⏱️ + 19m 36s
10 671 tests +  3  10 671 ✔️ +  4  0 💤 ±0  0 ❌  - 1 
51 571 runs  +12  51 571 ✔️ +13  0 💤 ±0  0 ❌  - 1 

Results for commit fb9614b. ± Comparison against base commit 48a96c1.

[majastrz]