Harmonize approaches to handling errors and exceptions

Do a timeboxed Spike to:

• take stock of current situation;
• take input from pre-construction design (TM certainly available, but others where possible);
• capture some scenarios;
• take into account standard TANGO patterns for errors and exceptions;
• analyse and propose some guidelines for SKA standar patterns for handlings errors and exceptions;
• share with everyone and request feedback;
• respond to feedback.

Note that a "one size fits all" approach is unlikely to be appropriate and the guidelines should acknowledge this. Sometimes an error will mean "stop everything", sometimes sometimes its just "we've lost a little sensitivity, but we can carry on". The guidelines are more about how to handle these sorts of situations.

Further work could be done in the follow up: SP-709