Request: Allow notifying only the requester on acceptance

When requesting assistance (e.g. room & vc assistance), a confirmation email is sent to all the event managers when the request is accepted, which can be spammy in certain situations.
The idea would be implementing a system to only notify the requester. This can be a hardcoded setting on the request definition.

No files or tests are named. Start by locating the request definition and the acceptance-email recipient logic in the Python application, then determine how requester and event-manager recipients are selected. Done means a request can be configured to notify only its requester when accepted.

Written by the indexing model from the issue text.