[Issue Tracker] Add ‘Instrument’ from a drop down of all instruments

For the Issue Tracker, add dropdown field to select the ‘Instrument’ from a drop down of all instruments.


**Related to:**
- https://redmine.cbrain.mcgill.ca/issues/11057
- https://github.com/aces/Loris/issues/4150
- https://github.com/aces/Loris/issues/8328