fix: Toggle Event Effect Chooser Data Typing

[phroggster]

Description of the Change

• Loading a dropdown-select element with no values available to bind to it previously locked it into string-handling mode.
• This broke the Toggle Event effect on initial creation, which expected object-handling mode, but supplied no initial binding values.
  • As such, the initially saved effect data used the name of the event, instead of the unique ID of it.
• Added an optional one-way "value-mode" attribute to dropdown-select to force it to operate in either object or string mode, or default to prior behavior when unspecified.
• Fixed two arrow-parens.
• Beyond original scope:
  • Have the effect's group name track renaming of event sets, which would cause similar problems in the effect's UI.

Applicable Issues

#3006

Testing

Tested Toggle Event creation and editing thoroughly, plus a handful of others. I still need to verify whether a similar issue could occur in approximately 4 other places, at which point I'll just tack them on to here sometime tonight.

Screenshots

Newly-created effect before:

{"id":"c99f52f9-2875-48e5-b1c2-3295988887a1","type":"firebot:toggle-event","active":true,"toggleType":"disable","selectedGroupName":"General Events","selectedEventId":"Sub"}

Newly-created effect after:

{"id":"1fad718c-0da3-4416-aeff-d9894407f0e9","type":"firebot:toggle-event","active":true,"toggleType":"toggle","selectedGroupName":"General Events","selectedEventId":"0eaf3180-ae07-11ed-a61c-31cd9d099aeb"}

[phroggster]

It looks like the other locations where a similar issue could have potentially been reached all have other means of preventing it from occurring. Either length checking, hard-coded choices, or no potential way to initialize the control in an empty manner, then later show it.

That makes me re-question the approach I took here, but this PR does keep the UX identical while avoiding the issue. It also allows other places to be able to change the value mode in their template should they desire to, so I'm keeping it. Let me know if you'd prefer changing the UX of this one effect instead of the added attribute, or if you've got a better idea to deal with this.

[ebiggz]

Thanks for this fix - getting into the weeds with angularjs' archaic attribute data binding is never a fun time so I empathize.