Preserve nullability when loading resource-derived type from ARM JSON template

[jeskew]

Resolves #13526

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 8163468825)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 8163468825

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 8163468825"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 8163468825

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 8163468825"

[github-actions]

Test Results

    66 files   -     33      66 suites   - 33   22m 36s ⏱️ - 21m 17s
10 678 tests  -     19  10 677 ✅  -     19  1 💤 ±0  0 ❌ ±0 
25 246 runs   - 12 616  25 244 ✅  - 12 615  2 💤  - 1  0 ❌ ±0 

Results for commit 7c51eff. ± Comparison against base commit b41394e.