feature(subset): add Challenge subset type

[Jamiras]

https://discord.com/channels/310192285306454017/1488177530786680852/1488273598375530517

Challenge subsets work like Bonus subsets. They will be loaded with the Base set when opted-in. The only difference between Bonus subsets and Challenge subsets is Challenge subsets are opt-out by default.

Currently, to make a subset not load with the Base set, the subset has to be marked as Specialty, which requires a unique hash, so a patch must be applied even if the subset is completely compatible with the unmodified ROM.

Challenge subsets allow a distinction between stuff that can be earned while playing the Base set normally (Bonus subsets) and stuff that would be earned while playing the Base set in a specific way (Specialty subsets).

Rare item drops should remain as Bonus sets as there's no specific playstyle required to earn them.

Low-level runs, PoC runs, solo runs, speed runs, no-jumping runs, no upgrades runs, and other similar challenge-style runs should be Challenge subsets. Many of these are currently Specialty subsets so as not to confuse users with subset specific leaderboards and challenge indicators. As Specialty subsets, they still require patching, which is an undesirable barrier of entry that is not really needed.

Stage-specific challenges could remain in Bonus as they don't require a specific playstyle for the entire game. It will be up to the developer to determine how obtrusive the subset notifications are, and whether or not the player can lock themself out of most of the subset early in the playthrough. In those cases, things should be moved into a Challenge subset.

Specialty subsets will hopefully be largely eliminated. Any subset that doesn't require a patch should not require a patch. There are still some challenge runs that do require patching but don't affect the the Base set achievements. These would still be marked as Specialty and the Base set and other Bonus set achievements would be loaded with it. The most obvious example of this is Lazy Lakitu, which locks the camera in place.

A less obvious example of a potential Specialty subset is the SMB five minute run as it specifically uses the SMB+Duck Hunt ROM for timing purposes . But that's currently marked as Exclusive anyway; presumably to keep the Base set leaderboards from being distracting during the subset speed run.

Exclusive subsets still load without the Base set or any other Subsets. To be very clear, none of the existing subset types are affected. This is just adding a new subset type that acts like Specialty without requiring a unique hash.