Samples/add multitenancy samples v2

[mheidari988]

Summary

• Fix OpenAPI generation for minimal APIs so tenant route parameters are preserved by reading RoutePattern when attribute templates are missing, with regression tests.
• Bump the multitenancy sample/docs to v0.2.7 package references.

Testing

• dotnet test
• Other (add details):

Checklist

• Includes docs/changelog updates if user-facing
• Adds/updates tests
• Keeps public API surface minimal and backward compatible (or documents breaking change)
• PR scoped to a single concern/module where possible

Notes

• Breaking changes? If yes, describe impact and migration.
  • None.
• Related issues/links:
  • N/A