Add type definitions for providers()

[anthony-c-martin]

Contributing a Pull Request

If you haven't already, read the full contribution guide. The guide may have changed since the last time you read it, so please double-check. Once you are done and ready to submit your PR, run through the relevant checklist below.

Contributing a feature

• I have opened a new issue for the proposal, or commented on an existing one, and ensured that the Bicep maintainers are good with the design of the feature being implemented
• I have included "Fixes #{issue_number}" in the PR description, so GitHub can link to the issue and close it when the PR is merged
• I have appropriate test coverage of my new feature

Fixes #1630

[majastrz]

Btw, I opened an internal task to clarify it in JSON functions docs. It's completely non-obvious that it's sometimes returning a single object and sometimes an array.

[codecov-io]

Codecov Report

Merging #1877 (01c97a7) into main (cf4e7ec) will increase coverage by 0.44%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1877      +/-   ##
==========================================
+ Coverage   95.11%   95.55%   +0.44%     
==========================================
  Files         371      367       -4     
  Lines       21929    21822     -107     
  Branches       15        0      -15     
==========================================
- Hits        20857    20853       -4     
+ Misses       1072      969     -103     

Flag	Coverage Δ
dotnet	95.55% <100.00%> (+0.01%)	⬆️
typescript	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/Bicep.Core.IntegrationTests/ScenarioTests.cs	100.00% <100.00%> (ø)
...UnitTests/Assertions/JTokenAssertionsExtensions.cs	95.65% <100.00%> (ø)
...cep.Core/Semantics/Namespaces/AzNamespaceSymbol.cs	100.00% <100.00%> (ø)
src/vscode-bicep/src/utils/telemetry.ts
src/vscode-bicep/src/extension.ts
src/vscode-bicep/src/utils/logger.ts
src/vscode-bicep/src/language/client.ts
src/Bicep.Core.UnitTests/Utils/CompilerFlags.cs	40.00% <0.00%> (+6.66%)	⬆️