Fixes for issue #14770

[anthony-c-martin]

Closes #14770

• Resolve file system paths for a local extension relative to the bicepconfig.json file
• Raise diagnostics rather than a fatal exception if an invalid path is specified

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 10392146656)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 10392146656

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 10392146656"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 10392146656

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 10392146656"

[github-actions]

Dotnet Test Results

    72 files   -     36      72 suites   - 36   22m 37s ⏱️ - 8m 56s
11 039 tests  -     16  11 039 ✅  -     16  0 💤 ±0  0 ❌ ±0 
25 854 runs   - 12 911  25 854 ✅  - 12 911  0 💤 ±0  0 ❌ ±0 

Results for commit aa4c47c. ± Comparison against base commit e40c9fc.

♻️ This comment has been updated with latest results.

[shenglol]