Initiative coordinator and faciltiator appointments

Problem/Motivation

Following up on this comment → from xjm.

The second half of this point, from #8.3 → of the other issue needs to be resolved.

Core committers should also maybe be able to appoint initiative coordinators; it is weird for that role to suddenly be harder to get into than actually being a committer. Maybe initiative coordinators should be appointed by consensus between the initiative facilitators and product managers? As well as any existing coordinator for a given initiative (similarly as what is done for subsystem maintainers), but the language isn't there yet for subsystem maintainers so maybe that last bit is out of scope.

Steps to reproduce

Proposed resolution

Remaining tasks

Postponed on #3367191: Speed up decision making: define the project lead as an arbitrator/tie breaker instead of ultimate decision maker →

User interface changes

API changes

Data model changes