[CL]: Improve KVStore Entry

[czarcas7ic]

Background

The current Owner | Pool ID | Position ID -> Position ID KVStore returns values like so:

addr1|1|1->1
addr1|1|2->2
addr1|2|3->3
addr2|1|4->4
addr2|1|5->5

We should instead key Owner | Pool ID -> list of Position IDs like so:

addr1|1|->[1, 2]
addr1|2|->[3]
addr2|1|->[4,5]

Another improvement that can be made is with with current Pool ID -> Position ID mapping, and switching it to a Pool ID -> List of Position IDs mapping as well (similar to what was explained above)

Suggested Design

• Change the store logic in createPosition and removePosition
• Update tests to ensure any new logic added is covered