Run/compile cooldown

[nionata]

We need to implement some sort of compile cool down. We don't want students spam clicking the run button and flooding the compile server w/ redundant requests. Here is an example of how leetcode limits their remote code execution:

This could be very simple and lead to a robust solution with the help of #6

Additionally, we need the client to limit the number of requests it sends.

Backend

• Check the last student submission for a time threshold and/or a workspace diff

Frontend

• Render an error message when trying to compile within the cool down
• Render an error message when trying to compile the same code as last time
• Have a request counter - if it hits the counter log an err message / try again

[rennemannd]

This is good to get done quickly, I'll get on it!