[Request] Maximum scan depth/file count option

[Deterous]

Similar to #339 or perhaps in replacement of it, this is a request for a BOS option that limits file scanning to a certain depth from the initial scan folder path, or a limit on the number of files that will be scanned.

The motivation behind this request is the same as #339, to limit time spent scanning via capping how much "effort" BOS employs when scanning. This may persuade potential users to use BOS such as those who prefer to leave protection scanning off in MPF due to the current time spent scanning (e.g. coverdisc dumpers). For example in MPF, a default scan depth of 3 with a "full scan" option off by default, or even a custom maximum search depth option in MPF. Alternatively, it could limit BOS to scanning X number of files, with an option to remove the limit and do a "Full Scan".

The theory behind a maximum search depth (vs. bounded per-file scan time) is that protections/packers/etc are more likely to occur higher in the directory structure, while the mass of game assets that take up a large chunk of scanning time without any useful detections are more likely to occur at lower depths. The theory behind a file count limit is that it would work on folder structures that are deep but small.