Alert ownership for multiple teams/owners

### Problem Statement

Imagine there is a monorepo, and its main "project" has multiple shared-ownership teams.

The Sentry project has 4 "project teams" assigned, but as the alerts can only have a single person or team as the owner the other teams of that project cannot edit the alert.

It would be great if the alerts either a) shared/inherited the project owners or b) could also have multiple owning teams.

### Solution Brainstorm

All or nothing solution: by setting no owner of the alert. Everyone has access to it. - This is nice, but does not give the granular control like with multiple owners.

┆Issue is synchronized with this [Jira Improvement](https://getsentry.atlassian.net/browse/FEEDBACK-1749) by [Unito](https://www.unito.io)