fix: Properly sort roles for Role#position

[vladfrangu]

Please describe the changes this PR makes and why it should be merged:

Sorting by position was wrong for roles (thanks to inconsistencies when it comes to rawPosition (thanks Discord)), and would sort bottom->top, while channels were top->bottom (depending on the channel type, and parent, if applicable).

This PR solves that, by implementing a positionSort argument for Util.discordSort.

Now, roles are sorted top->bottom (like on the client) and channels sort the same was as before

Status

• Code changes have been tested against the Discord API, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

Semantic versioning classification:

• This PR changes the library's interface (methods or parameters added)
  • This PR includes breaking changes (methods removed or renamed, parameters moved or removed)
• This PR only includes non-code changes, like changes to documentation, README, etc.

[vladfrangu]

Seems like this doesn't happen anymore... Will reopen if I encounter it again