Update TPG300 OPI to support TPG500

[boeuf-codes]

Description of work

• Add status RBVs for each pressure gauge
• Title now controlled by PV so displays TPG500/TPG300 depending on model
• Hide 'Relay contact status' group and A/B threshold violation LEDs for TPG500s
• Add RBV for device error status
• Update OPI description

Ticket

#7458

---

Code Review

• Is the code of an acceptable quality?
• If the change is to an OPI, does the check_opi_format.py script in C:\Instrument\Dev\ibex_gui\base\uk.ac.stfc.isis.ibex.opis pass?
• Do the changes function as described and is it robust?
• Is there associated PR for the release notes?

Final Steps

• Reviewer has also merged the release notes

[esmith1729]

looks good, and switches between 500 and 300 depending on IOC