RM-45: Add predefined close reasons

[biast12]

RM-45

Description

Adds support for predefined close reasons, which are set per panel on the dashboard:

• /close and /closerequest suggest the panel's close reasons as you type.
• The Close with Reason form shows a reason picker. It also shows a text box when the panel allows custom reasons. A picked reason wins over typed text.
• The archive's Edit Close Reason button uses the same form, with the current reason pre-selected.
• If the panel doesn't allow custom reasons, any reason given must be one of its close reasons. Closing without a reason still works.

Panels without close reasons, and tickets without a panel, behave exactly as before. If the lookup fails, the worker falls back to today's behaviour. System closes (auto-close, member leave, close request accept and timer, dashboard relay) are unchanged.

Requires:
TicketsBot-cloud/database#47
TicketsBot-cloud/locale#252

Type of Change

• Bug fix
• New feature
• Breaking change

Testing

• Check that everything works as it does now (there should be no change in behaviour)
• Add a close reason, check if it come up when you run /close and /closerequest
• Use the close with reason button, does the dropdown come up with the options?
• Add something in both the options and submit - only the selected predefined option should be the close reason
• Turn off Allow Custom Close Reasons - only the selects should be allowed and appear in the close with reason modal

Checklist

• My code follows the style of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works

[github-actions]

Resolved

No blocking labels remain.

[BenHall-1]

Ready to bump

[biast12]

@BenHall-1 bumped!