fix(ranks): rankLadder variable register

[CKY-]

Description of the Change

register rankLadder variable

Applicable Issues

#2995

Testing

sent chat message on rank ladder update event
@$userDisplayName[$user] has achieved the rank of $newRank $rankValueDescription[$rankLadder, $newRank]!
@phroggie has achieved the rank of regular 3000 test1!

Screenshots

[phroggster]

Once this is merged, a Chat Message effect can use @$userDisplayName has achieved the rank of $newRank ($rankValueDescription[$rankLadder, $newRank])! to get a similar message to the default message template in a Viewer Rank Updated event. Until merging, the closest we can get in the nightlies is @$userDisplayName has achieved the rank of $newRank! (or @$userDisplayName[$user] has achieved the rank of $newRank! in the v5.63.2 release).