Converted ophyd enum types to uppercase.

[canismarko]

The next version of ophyd-async will enforce capitalization for attributes on enum types. Currently, these are recommended by convention, and so doing this now shouldn't cause any backwards compatibility issues.

Things to do before merging:

• add tests
• write docs
• update iconfig_testing.toml
• flake8, black, and isort

[canismarko]

Overall, looks good but I think we can change the names of the enum values.

[canismarko]

Why aren't we using numerals for this? E.g. "1_HUNDRED"?

[sterbinsky]

Noted message when opening Ion Chamber windows in firefly:
[ERROR ] - Can not change value to <ScanInterval.SCAN_0_2: '.2 seconds'>. Not an option in PyDMComboBox
Possibly related to the changes here, but also maybe not. Overall though, everything appears to work in spite of error messages.

[canismarko]

Noted message when opening Ion Chamber windows in firefly: [ERROR ] - Can not change value to <ScanInterval.SCAN_0_2: '.2 seconds'>. Not an option in PyDMComboBox Possibly related to the changes here, but also maybe not. Overall though, everything appears to work in spite of error messages.

Yes, actually it is. The options for the labjack scan parameter is actually ".2 second" not ".2 seconds". I'll fix it.

[canismarko]

I think that error happens when the PyDM widget tries to set the value from the PV before the enum combobox has updated the list of available options. I don't think it's related to this PR, so I will merge this one, and put this bug into a separate issue for later: #330

Thanks @sterbinsky!