Check build, execute and append status before running a scan.

[gkalua]

Investigate the busy record within the flyscanning trajectory and return the relevant error messages.

Background:

When a Flyscan is run using a bluesky plan, we notice that if any of these vital commands fail, 'Build Profile', 'Append Points', and 'Execute Profile', expectedly, the scan does not run. However, on the run engine, the failure is not reported and instead waits forever and eventually times out.

Acceptance Criteria:

• Show error message when build, execute or append fails.
• End the wait if any of the above commands fails.

[coretl]

There are 2 issues here:

• We currently get a timeout from observe_value, but I would expect that it should break out of that loop as soon as the execute stop, as we pass

  ophyd-async/src/ophyd_async/epics/pmac/_pmac_trajectory.py

  Line 106 in bb7c989

  done_status=execute_status,

  This needs checking to see if the busy record is doing the right thing
• When we break out of the loop we should check the Status and Message PVs for the action, using the race condition defeating logic from areaDetector:

  ophyd-async/src/ophyd_async/epics/adcore/_core_logic.py

  Lines 127 to 146 in bb7c989

  	await status
  	state = None
  	try:
  	async for state in observe_value(
  	self.driver.detector_state, done_timeout=state_timeout
  	):
  	if state in self.good_states:
  	return
  	except TimeoutError as exc:
  	if state is not None:
  	raise ValueError(
  	f"Final detector state {state.value} not in valid end "
  	f"states: {self.good_states}"
  	) from exc
  	else:
  	# No updates from the detector, something else is wrong
  	raise TimeoutError(
  	"Could not monitor detector state: "
  	+ self.driver.detector_state.source
  	) from exc