Harmonize approaches to handling errors and exceptions: Followup to SP687

This is a Clone of SP687 to retain the information, we timeboxed that as a Spike.

This is a follow up ticket for that.

Based on the guidelines in SP687 the teams will:s

1. Design a POC specifically to implement guidelines in the TMC code
2. Implement the exception handing in the TMC nodes.
3. Test and document the learnings from the same
4. Update if needed  Standardised approach to error and exception handling and update an implementation map for other components 

Originated from SARCH Team

Update:

During PI#7 planning meeting, the scope of this feature is agreed as follows:

• Implement exception handling for one of the operations in the TMC (e.g.assign resources).
• TMC shall inherit custom exception class from one of the most appropriate Python/Tango exception class
• Raise the exception at appropriate place(s) and catch them
• Log the exceptions
• Demonstrate propagation of the exception across Tango devices
• Implement a scenario where violation of a business rule results into raising an exception
• This will be a proof of concept implemented in the MVP.
• Some aspects such as UI display will not be covered.
• The exception handling guidelines will be updated with learning/changes, if any