setup playbook and heartbeat for isolated deployments

* Allow isolated_group_ use in setup playbook
* Tweaks to host/queue registration commands complementing setup
* Create isolated heartbeat task and check capacity
* Add content about isolated instances to acceptance docs

awx/settings/defaults.py

@@ -609,6 +609,8 @@ AWX_ISOLATED_CHECK_INTERVAL = 30
 
 # The timeout (in seconds) for launching jobs on isolated nodes
 AWX_ISOLATED_LAUNCH_TIMEOUT = 600
+# The time between the background isolated heartbeat status check
+AWX_ISOLATED_PERIODIC_CHECK = 600
 
 # Enable Pendo on the UI, possible values are 'off', 'anonymous', and 'detailed'
 # Note: This setting may be overridden by database settings.