Remove members once a subscription is exhausted

[reyraa]

Description

Muzikie Blockchain should automatically remove all members once the subscription is exhausted. A subscription is exhausted if the remaining consumable is less than required for streaming an audio. Once exhausted, the remaining balance should be transferred to the dev account.

Acceptance Criteria

• When users try streaming with a subscription and the remaining consumable is not enough we should preform an exhaustion cleanup action.
• Exhaustion cleanup action removes all members from the subscription, meaning, sets the members of the subscription to an empty array, and removes the shared value of each member.
• Sufficient unit test is desired.