feat: more CustomRole and CustomAbility register methods that dont rely on attribute

[Someone-193]

Description

Describe the changes
Some people were complaining CustomRole.RegisterRoles(); and CustomAbility.RegisterAbilities(); didnt work (mostly cuz they didnt have the respective attribute) but considering these people dont really expect to use them, I feel like I might as well just add a really simple register method.

What is the current behavior? (You can also link to an open issue here)
You MUST use attributes to use Exiled register methods

What is the new behavior? (if this is a feature change)
You can use new methods to register all classes that derive from CustomRole / CustomAbility (and arent abstract)

Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
Don't believe so

Other information:
Haven't tested, I @'d someone on discord to hopefully get them to test it themselves, but you guys can provide any thoughts you want here while we wait.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentations

Submission checklist

• I have checked the project can be compiled
• I have tested my changes and it worked as expected

Patches (if there are any changes related to Harmony patches)

• I have checked no IL patching errors in the console

Other

• Still requires more testing