Added hub_routing_preference to connectivity advanced configuration

[QBY-MarkusMaring]

Overview/Summary

This PR adds the hub_routing_preference option to the advanced configuration section of azurerm_virtual_hub.
The default value is the same as for the azurerm provider ("ExpressRoute") so by default no changes will occur when upgrading.
There doesn't seem to be documentation for advanced configs that needs to be updated, let me know if I just missed it and I will update it.

This PR relates to issue #861

See azurerm documentation for this option here

This PR fixes/adds/changes/removes

1. Adds hub_routing_preference option

Breaking Changes

Testing Evidence

In a local test I've modified the custom_settings_by_resource_type block of tests/modules/settings/settings.connectivity.tf to include the following:

azurerm_virtual_hub = {
  virtual_wan = {
    (var.primary_location) = {
      hub_routing_preference = "ASPath"
    }
  }
}

Planning tests/modules/test_003_add_mgmt_conn will show that the hub_routing_preference for the primary location hub has changed accordingly and that the secondary location hub maintains it's default configuration "ExpressRoute":

As part of this Pull Request I have

• Checked for duplicate Pull Requests
• Associated it with relevant issues, for tracking and closure.
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Performed testing and provided evidence.
• Updated relevant and associated documentation.

[QBY-MarkusMaring]

@microsoft-github-policy-service agree company="q.beyond AG"

[matt-FFFFFF]

/azp run unit

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