Improve emissions module and make it more flexible for a permissionless set

[lumtis]

Describe the Issue
This epic track tasks to improve the emissions module and allow moving toward a design when adding a new observer in the set would follow more permissionless rule.

• Adding more parameter to configure the rewards
• Implement full mechanism for deincentivizing non-correct behavior

Tasks

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1. Enable ObserverSlashAmount again in the param #1898
   m:emissions +1
   
2. Create a parameter for RewardPerBlock #1897
   m:emissions +1
3. Moving distribution logic in keeper package #1792
   m:emissions +1
4. emissions : improve slashing #1654
   m:emissions +1
5. zetacore : Delete Ballots after distribution #942
   m:emissions +1
6. refactor : remove unused params in emssions module #1852
   m:emissions +1
   
7. Cleaning up unused functions and variables and add more documentation #1813
   code-quality m:emissions +2
   
8. emissions: Withdraw to alternative address and auto withdraw max amount #3078
   m:emissions +1

[lumtis]

Putting this v18 for now, we will reevaluate priority after v17 upgrade