RFC: make participants aware of their conversation permissions

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Is your feature request related to a problem? Please describe.
It's known for moderators, but not for the participants itself, or could be found in some non-obvious places, although frontend is receiving and can use this data

Describe the solution you'd like
Conversation settings => Setup overview => List of permissions for given conversation

Describe alternatives you've considered
Context messages / tooltips where it's applicable

Example of usage (bitiwise + negation check):

videoButtonTooltip() {
	if (~this.conversation.permissions & PARTICIPANT.PERMISSIONS.PUBLISH_VIDEO) {
		return t('spreed', 'You are not allowed to enable video')
	}
},

Start with the frontend conversation settings and Setup overview, then trace how conversation permissions are received and currently exposed to participants. Review the proposed permissions list and the alternative context messages or tooltips, including the shown video-permission example. Done means participants can find their conversation permissions and understand applicable restrictions.