fix: hostname routing in module/device

[cheatsheet1999]

Two bug fixes from bug bash:

• az iot hub device-identity connection-string show
az iot hub module-identity connection-string show

  Update: Reject --hostname-type service.

• az iot hub generate-sas-token

  Update: Add --hostname-type / --ht. The audience (sr=) defaults to:
  - service hostname for hub-scoped tokens (no -d)
  - device hostname for device/module-scoped tokens (-d / -d -m)
  - classic, device and service are explicitly selectable.

[Copilot]

Pull request overview

This PR adjusts IoT Hub hostname selection behavior for device/module connection-string commands and for SAS token generation, aligning “audience” (sr=) routing with GWv2 TLS 1.3 hostnames and adding test coverage for the new permutations.

Changes:

• Reject --hostname-type service for device-identity connection-string show and module-identity connection-string show.
• Add --hostname-type/--ht to az iot hub generate-sas-token and route SAS audience (sr=) based on scope and selected hostname type.
• Add unit + integration tests validating hostname-type permutations and sr= audience values; bump extension version and update changelog/help examples.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
HISTORY.rst	Documents the bug fixes and new --hostname-type behavior for SAS tokens.
azext_iot/constants.py	Bumps extension version to 0.31.0b2.
azext_iot/operations/hub.py	Implements SAS audience hostname routing and rejects service hostname type for device/module connection strings.
azext_iot/_params.py	Adds --hostname-type/--ht parameter to iot hub generate-sas-token.
azext_iot/_help.py	Adds new generate-sas-token examples demonstrating --hostname-type.
azext_iot/tests/iothub/core/test_iothub_utilities_unit.py	Adds unit tests for SAS audience routing + CS-show service-hostname rejection.
azext_iot/tests/iothub/core/test_iothub_utilities_int.py	Adds integration coverage for hub-level SAS hostname-type permutations.
azext_iot/tests/iothub/devices/test_iothub_devices_int.py	Adds integration coverage for device-scope CS-show + SAS hostname-type permutations.
azext_iot/tests/iothub/modules/test_iothub_modules_int.py	Adds integration coverage for module-scope CS-show + SAS hostname-type permutations.

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