Make useful scripts into a dodal utility

[stan-dot]

          Tagging @stan-dot as this is general good info. So to look up the type of a PV I do the following:

• python2 /dls_sw/work/useful-scripts/find-pv.py BL20I-EA-DET-06:ERASE
• This showed me the PV was defined in /dls_sw/work/R3.14.12.7/support/BL20I-BUILDER/iocs/BL20I-EA-IOC-05/db/BL20I-EA-IOC-05_expanded.db as a bo record.
• EPICS record types are documented at https://epics.anl.gov/base/R3-15/7-docs/RecordReference.html
• If you look at https://epics.anl.gov/base/R3-15/7-docs/boRecord.html you can see that bo records take values of 0 or 1, but they can define ZNAM and ONAM which are user friendly names for the 0/1 states
• So if we do:

$ caget BL03I-EA-XSP3-01:ERASE.ZNAM BL03I-EA-XSP3-01:ERASE.ONAM
BL03I-EA-XSP3-01:ERASE.ZNAM    
BL03I-EA-XSP3-01:ERASE.ONAM    

We can see that both are blank compared to a PV of the same type I found elsewhere:

$ caget BL03I-MO-SGON-01:CS1:DeferMoves.ZNAM BL03I-MO-SGON-01:CS1:DeferMoves.ONAM
BL03I-MO-SGON-01:CS1:DeferMoves.ZNAM Defer Off
BL03I-MO-SGON-01:CS1:DeferMoves.ONAM Defer On

• Given they're both blank this is why your string enum complains if they're anything else. Obviously this won't actually work in production as if you set blank on the PV how does it know which one you actually need?

So, we have some choices:

1. Talk to controls and ask them to provide named states for the PV, or change the PV to a type that is more appropriate
2. Use an int - This will work but is a bit of a shame as it's not super clear that writing 1 to the erase is what you want to do
3. Use an IntEnum e.g.

class EraseEnum(int, Enum):
    ERASE = 1
    DONE = 0

But are you saying that didn't work? In which case we should probably open a discussion up about if this is a bug in ophyd_async

I prefer option 1 but it will be the most work. I can live with option 2 for now in the interests of just getting things done, maybe we can then put in a ticket with controls to improve it at a later date

Originally posted by @DominicOram in #524 (comment)