Configure dbformysql (3),digitaltwins (4),disk (2)

[ytsarev]

External name configuration of 3 resources in the dbformysql group:

• [x] azurerm_mysql_active_directory_administrator
• [x] azurerm_mysql_database
• [x] azurerm_mysql_server_key

External name configuration of 4 resources in the digitaltwins group:

• [x] azurerm_digital_twins_endpoint_eventgrid
• [x] azurerm_digital_twins_endpoint_eventhub
• [x] azurerm_digital_twins_endpoint_servicebus
• [x] azurerm_digital_twins_instance

External name configuration of 2 resources in the disk group:

• [x] azurerm_disk_pool
• [x] azurerm_disk_pool_iscsi_target

[ytsarev]

Removing resources request that are already implemented in https://github.com/upbound/official-providers/issues/434