Nanodac: Make an OPI

[DominicOram]

The nanodac ticket (ISISComputingGroup/EPICS-ioc#124) did not create an OPI as it was not necessary at the time. If this becomes necessary one should be created.

[KathrynBaker]

After 7 years one has not been created or asked for, should one be asked for we can create a new ticket at the time.

[Tom-Willemsen]

Reopening as useful for Hydrogen lab machines

[Tom-Willemsen]

PRs:

• Add basic Nanodac OPI ibex_gui#1841
• Ticket2196 #8949

OPI containing the key parameters, but not exhaustively allowing everything the IOC can do.