Add support for intentionally denying submitted tournaments

[hburn7]

Dependencies

• Add capability to submit a tournament with the intention of rejecting it. otr-api#357 (comment)

Objective

• Users with the admin permission should be able to intentionally deny tournaments when submitting them.

Implementation

• In the POST body, add new key rejectionReason = (user selected rejection reasons int) (see here)
• Rejection reason should be a multi-select dropdown menu with all rejection reasons in the linked file.
• If a user selects more than one rejection reason, use bitwise unions on the values (e.g. (1 << 1) | (1 << 2) => x -- use rejectionReason = x in the POST body).