Restrict the number of concurrent matches that a user is allowed to have.

[WilliamDormer]

In the swiping endpoint (may not be uploaded to main yet, if not look at the miniointegration), when the user wants like like, or dislike another person, and they already have the maximum number of concurrent matches, it should return and send an error to the frontend. The max number of concurrent matches should be stored as a global variable in the nodejs application. You can determine how many concurrent matches the person has by querying the swipes database table and searching for where the UUID of the sender is the person hitting the endpoint, and counting the number that is in the match state (i forget which integer represents the match, but it's in the code). A good starting number of concurrent matches would be 5, but it should be easy to change with one line.