Syncing challenges with ctfcli - option to turn off category syncing

[reteps]

Feature wanted:

• Command line flag or options to reuse challenge category if present, e.g. --reuse-category. This change could be made here

Reasoning:

We are usingctfcli to deploy challenges for our cybersecurity club as we run meetings related to them. Generally, we want a section of our CTFd to be "Work Ahead", where students can do challenges before meetings are run on them. We want to setup a CI hook that redeploys challenges every time a file is changed in CTFd.

When meetings are run, we create a category for the meeting and hoist the category to the top of CTFd. Then, we move the challenges we want from the vault into that category on CTFd. However, we might need to modify the challenge.yml file later. This causes issues, as if we sync, we have now accidentally changed the category from the meeting category back to the vault category.