SDK: updating the pollers for resourcemanager

[tombuildsstuff]

This PR fixes a number of issues identified when enabling the base layer in hashicorp/terraform-provider-azurerm#20688, namely:

1. Some Resource Manager APIs return the LRO OperationStatus URI on a verbose hostname (including the port), such that the check we have present here isn't strictly needed (else we fail comparing https://management.azure.com to https://management.azure.com:443, which whilst technically the same the LRO URI isn't guaranteed to be on the same port afaik)
2. Some Resource Manager APIs (such as SignalR) return an LRO Status of Running rather than InProgress, as such this PR adds an exception for this
3. Introduces a Delete LRO - which (after deleting a resource) will validate that the resource ultimately disappears

[jackofallops]

LGTM 👍