Fix button using both databinding and manual updates

[Tom-Willemsen]

Description of work

Root issue was using both databinding and asyncExecs to update the same UI state.

To test:

• Start IBEX GUI with NICOSDAEMON switched OFF
• Run button is disabled
• Add some actions in the script generator
• Run button remains disabled
• Start NICOSDAEMON
• Run button becomes enabled after a short delay
• Restart the client, run button should be enabled
• Kill NICOSDAEMON, run button should disable

This is manual, I don't think there is much cost/benefit to adding an entire squish test for this (and it can't be tested at the unit-test level as it's all UI code).

Ticket

Fixes ISISComputingGroup/IBEX#8697

Acceptance criteria

• State of "run" button always matches state of underlying NICOS connection

Unit tests

This is a change in the UI layer - it is not possible to unit test easily. This is best-tested manually.

---

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