Use IAsyncSwaggerProvider in CLI tofile command

[bt-Knodel]

Summary

The CLI's tofile command resolves ISwaggerProvider and calls the synchronous GetSwagger(), which internally uses GenerateOperation(). This sync path only invokes IOperationFilter registrations — IOperationAsyncFilter registrations are silently skipped.

This means any project using OperationAsyncFilter() gets correct output from the runtime swagger middleware but missing output from dotnet swagger tofile, leading to inconsistencies in generated clients (e.g., via Orval/NSwag).

Changes

• Make CommandRunner and Program.Main fully async — no sync-over-async (GetAwaiter().GetResult())
• The _tofile command prefers IAsyncSwaggerProvider.GetSwaggerAsync() when available, falling back to ISwaggerProvider.GetSwagger() for backward compatibility
• Add Authorization test WebSite demonstrating real-world async filter: SecurityRequirementsAsyncOperationFilter resolves authorization policies via IAuthorizationPolicyProvider.GetPolicyAsync() and adds security requirements to operations
• Integration test snapshots and CLI test for the new WebSite

Test plan

• All existing CLI and integration tests pass
• New Can_Generate_Swagger_Json_With_Async_Operation_Filters test verifies async filter output via CLI
• New Authorization WebSite validates real-world use case: async operation filter resolves authorization policies via IAuthorizationPolicyProvider.GetPolicyAsync() and documents security requirements on protected endpoints
• Backward compatible — falls back to sync provider if async provider is not registered

[bt-Knodel]

The issue #1661 appears to have missed the CLI implementation of Swagger. So async filters registered in the application are not called. Happy to adjust based on feedback, but would love to be able to use async policy filters with swagger cli.

[martincostello]

Just a few small style nits.

[martincostello]

Looks like some tests need fixing.

[bt-Knodel]

Added the missing Kiota files to fix the test.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.04%. Comparing base (d22870e) to head (034e1e3).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3910   +/-   ##
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  Coverage   95.04%   95.04%           
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  Files         111      111           
  Lines        3958     3958           
  Branches      801      801           
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  Hits         3762     3762           
  Misses        196      196           

Flag	Coverage Δ
Linux	95.04% <ø> (ø)
Windows	95.04% <ø> (ø)
macOS	95.04% <ø> (ø)

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