feat(CL Fees): implement creating fee accumulator at pool creation

[p0mvn]

Background

In #3893, we prototyped the concentrated liquidity fees.

Now, we need to split that PR into multiple components with tests.

This issue focuses on implementing and testing the createFeeAccumulator method and its dependencies. The method is to be called at pool creation in InitializePool.

We also need to add appropriate godocs and tests to all new logic.

Suggested Design

From #3893, we need to extract this method, add tests for it,

Next, we need to call it from InitializePool. InitializePool should also be tested to make sure that the accumulator is initialized correctly.

Relevant Resources

The following resources were used to implement the accum package that is required for implementing concentrated liquidity fees:

• General Simplified Abstraction: https://uploads-ssl.webflow.com/5ad71ffeb79acc67c8bcdaba/5ad8d1193a40977462982470_scalable-reward-distribution-paper.pdf
• Original API: https://hackmd.io/EUFXVr9_Roykx3jE9NNRzw
• F1 Fee Distribution (More complex use cases): https://drops.dagstuhl.de/opus/volltexte/2020/11974/pdf/OASIcs-Tokenomics-2019-10.pdf

Dependencies

This issue is blocked on: #3903 being merged. Branch off of #3903 if starting before its completion

Acceptance Criteria

• createFeeAccumulator helper is implemented
• tested with coverage maximized
• call createFeeAccumulator in InitializePool in x/concentrated-liquidity
• tests for InitializePool added to make sure that the accumulator is initialized correctly