This PR adds the following
* Supervisor v1 API application actions now return HTTP status code 423 when locks
are preventing the action to be performed. Previously this resulted in a
503 error
* Supervisor API v2 service actions now returns HTTP status code 423 when locks are
preventing the action to be performed. Previously, this resulted in an
exception logged by the supervisor and the API query timing out
* Supervisor API `/v2/applications/:appId/start-service` now does not
check for a lock. Lock handling in v2 actions is now performed by each
step executor
* `/v1/apps/:appId/start` now queries the target state and uses that
information to execute the start step (as v2 does). Previously start
resulted in `cannot get appId from undefined`
* Extra tests for API methods
Change-type: patch
Connects-to: #1523
Signed-off-by: Felipe Lalanne <felipe@balena.io>
