Focus failing must retry in the completion handler

Currently, the autofocus procedure can be retried by the Focus module. The number of retries is hardcoded, and the trigger to retry is done in the middle of the code, shortcutting notification, flag and state management.

The management of the local retry mechanism must be done in the completion handler. Three different MRs are needed:

• !176 (merged) - Add a test to testEkosFocus explicitly showing the issue.

• Create an Ekos option to store the number of retries, validate with a test. Not desirable.

• Move the retry mechanism to the completion handler of Focus. Make sure the focuser returns to the original position while the module settles. Make sure the status does not change if there is a retry left, and trigger the retry. Validate with a test. There is no issue in that situation, because the autofocus procedure is already aborted at that point.

• !176 (merged) - Validate Focus behaviour when guiding deviation returns to normal and Capture requests a refocus.

• !225 (merged) - Fix abort signal missing when Focuser ends at the same position as initial one.

• !212 (merged) - Safer Focuser loss, direct stop from UI, failure management and linear robustness.

• - Regression on polynomial curve rendering.