Refactor and generalise TPG300 emulator

[boeuf-codes]

Description of work

• Update/fix docstrings
• Rename tpg300 emulator to tpgx00 emulator

device.py:

• Add properties to support new commands
• Refactor to store enum members rather than explicit values (in emulator properties)

stream_interface.py:

• Add protocols for TPG 300 and 500 models
• Refactor to handle enum members from device.py
• Add methods to protocols to translate enum members to values

Ticket

#7458

[zsoltkebel]

Because the commands to the device don't all have the same terminator (namely the command doesn't have any, all the others have CR LF) the device seems to be waiting for the readtimeout every time on . These delays seem to have caused unreliability in testing so I reduced the readtimeout to 1 millisec. This should be fine as the commands are sent to the device as one block there should not be delay between parts of the same command.