feat: Find a way to make a role unique *within a group*

[sudojunior]

Currently (on rework/distribution) role groups have no logic to determine if a role they've been given should be unique (based on the logic of another group... which it doesn't have access to). Role groups themselves can have 'uniqueness' between the roles it has available and are more than capable of retrying within it's own role group (including if the specified role was already provided by another role group struct).

#8 may also throw another spanner in the works when attempting to determine if the role itself should be unique or if attributes should be unique (albeit that may be another thing entirely and an internal memory store may be a viable solution to simplify the transfer of data throughout - although it'd require another rewrite to achieve that, and with an expected degrading performance from initial / current stats at sub split-second timing could very quickly be increased to a few milliseconds for the most basic configuration).