User level status report, server rankings

[BrainFuck42]

Description: Add commands to view current leveling progress and xp breakdown for user and server ranking.

Use Case: Common levelling bot features, missing in initial implementation.

Proposed Solution:

• [x] command for member to see their current progress to next level and xp breakdown by category
• [x] command to see the current serverwide level ranking

Milestone: 5.2.2

Related Issues:

152 #217