Notifications Backend integration: Public group logic changes

[SathyaJayabal]

Public group logic changes - now excluding group like ["!CS", "!Zurich", "!Topgear"]

When a group is included in the filter like "groups": ["TestGroup"], then all members of the TestGroup will receive the notifications.

When a group is excluded in the filter like "groups": ["!TestGroup"], then all members excluding the members of TestGroup will receive the notifications.

So for example to send a public broadcast message the private group members of the CS, Zurich, Topgear groups will be excluded by using the filter "groups": ["!CS", "!Zurich", "!Topgear"]

cc @sachin-maheshwari @Oanh-and-only-Oanh

[SathyaJayabal]

verified on dev
When the groups filter is empty, then all users should receive the notification. But users belonging to any group. (eg:cognitive) do not receive the notification.

[SathyaJayabal]

@sachin-maheshwari , When a ! is used, the members who do not belong to the group do not get the notification.
Example:
Users TonyJ and dan_developer

TonyJ is a member of Blockchain, dan_developer is not.

If the groups filter is "groups": ["Blockchain"] then the notification is displayed correctly(only for tonyj), but if the groups filter is "groups": ["!Blockchain"], then the notification is not displayed for both the users, it should display for dan_developer.

[SathyaJayabal]

@sachin-maheshwari , verified on test env.
When a group is included in the filter like "groups": ["TestGroup"], then all members of the TestGroup receive the notifications.

When a group is excluded in the filter like "groups": ["!TestGroup"], then all members excluding the members of TestGroup receive the notifications.

[SathyaJayabal]

Can not be verified on production until a broadcast message is posted with the above filters.