Rewrite buffs

Closes #1832 (closed)

Effect Stacking Design Summary

• CC needs to be completely mitigated eventually, because any duration of stun can interrupt a cast
• X instances of Y type of cc in Z timeframe, otherwise the cc is ignored
• Squash's non-resetting stacks are an exception
• (future) CC resistance should be reworked into new stats to mitigate durations
• Effects should provide shouldStack(config)/incrementStack(config) methods to determine if a new effect of a matching type should be created or combined
• If an effect type template doesn't have shouldStack, always make a new effect
• XYZ check -> new duration mitigation -> shouldStack/incStack/new effect

Todo

• Track effects by IDs instead of by types
• Implement client-side effect objects w/ lifecycle (init, update, destroy)
• Move auras to effect template
• Implement sync-extending data to client effects
• Replace noMsg with silent flag
• Handle rezoning/death (should -stun/-slowed text show when an object is destroyed? what about when rezoning?)
• Implement shouldStack & incrementStack
• Fix uses of noMsg in addEffect
• Fix uses of new in addEffect
• Move buff icon management to client-side (remove onGetBuff/onRemoveBuff)
• Create and use new silent selfStun effect (for charging/etc, that doesn't cancel damage but stops movement and casting)
• Re-implement TTL stacking (create new method to stack ttl or create new effect if needed)
• Test sync-extending data to client effects
• Test (including with multiple players)
• Test shouldStack/incStack
• Remove debug logging
• IDs of persisted effects? (should the ID stay the same, so later callbacks can still remove it? ID counter's interaction with rezoning?)

API changes

• Removed noMsg from addEffect (use silent)
• Removed new from addEffect
• Removed removeEffectByName
• effects.syncRemove now takes only an effect ID (removed type and noMsg parameters)
• effects.removeEffect now takes only an effect ID (removeEffect destroys the effect first and remove it from the array and calls syncRemove; syncRemove removes it on the client-side)

Other Changes/Additions

• Removed double popup text from ice spear
• Client-side effects have lifecycle methods (init, update, destroy) and setVisible method
• Call this.defaultDamageText(removing: boolean) from custom effect init/destroy methods to create the default popup text
• Client-side effects also have this.obj, this.self (boolean)
• Server-side effects can call this.syncExtend(data: object) to call the matching extend(data) function with the data on the client-side effect object, or copy the properties from the data object on to the client-side effect object
• Server-side effects have this.silent for changing their behavior
• Updated existing spells/effects

Future

• Show target's effects in target UI
• Show party member's effects?
• Visually show durations/stacks of effects
• Indicate CC resists and when they kick in/wear off
• Tooltips on effect icons
• Add particles to existing effects?
• New stats to mitigate CC duration before applying
• Balance XYZ cc resist + duration mitigation stats
• Tags for mobs that make them fully immune to a type of cc (no knockbacks for bosses, etc; use canApplyEffect to check before doing pushbacks WITHOUT incrementing the cc resist counter)
• Cache onBeforeGetEffect requests (build a dict at startup instead of emitting on each buildEffect)
• Self vs non-self effect syncing (when needed)