Race condition of test_cases status updates and latency in submission status updates

[mohitejaikumar]

@hkirat Is it correct way of solving this problem since Redis in single threaded so it gives us feature of mutex lock which will help to resolve this . Since we want three things

1. Maximum time
2. Maximum memory
3. Submission Status (AC or Reject)

These all three things will be handled by submission-callback endpoint And Nextjs API used for polling will eventually show data on basis of this Redis

[SujithThirumalaisamy]

Resolved on #40