Add per panel ticket notification channel support

[biast12]

Description

RM-48
This PR is the dashboard part of adding per panel ticket notification channel support

Included: TicketsBot-cloud/worker#80
Needs this before accepting: TicketsBot-cloud/database#17

Type of Change

• Bug fix
• New feature
• Breaking change

Testing

Have global thread mode on, in a panel don't turn on per panel thread mode, but select a per panel notification channel, test if that works, then turn per panel thread mode on, change the per panel notification channel to use global and turn global thread mode off (this should error since you need a notification channel), then try the inverted with per panel thread mode (have global thread mode off and try to use the global notification channel, this should error too)

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

[BenHall-1]

db changes merged - please update

[BenHall-1]

LGTM 🎉