radicle: add notification count grouped by repo method
While the total notification count and the notification count by repo are needed, for most UIs users will want to see the total notification count grouped by repo. This new method will provide this without the need of checking all possible repos to see if they have notifications.
While the total notification count and the notification count by repo are needed, for most UIs users will want to see the total notification count grouped by repo. This new method will provide this without the need of checking all possible repos to see if they have notifications.
Rename method to count_by_repos
Fix test flake, change method name.