fix: incentive records get overwritten; key incentive records by ID

[p0mvn]

Background

We currently can only create one incentive record per pool id, uptime index, incentive denom and incentive creator:

osmosis/x/concentrated-liquidity/incentives.go

Lines 532 to 537 in bf4d3fe

	key := types.KeyIncentiveRecord(incentiveRecord.PoolId, uptimeIndex, incentiveRecord.IncentiveDenom, incentiveCreator)
	incentiveRecordBody := types.IncentiveRecordBody{
	RemainingAmount: incentiveRecord.IncentiveRecordBody.RemainingAmount,
	EmissionRate: incentiveRecord.IncentiveRecordBody.EmissionRate,
	StartTime: incentiveRecord.IncentiveRecordBody.StartTime,
	}

It looks like if I create the same gauge twice, the first one will get completely overwritten. Incentive records should have IDs in their keys to avoid this overwriting.

Suggested Design

Incentive records are keyed by ID

Acceptance Criteria

• add functional test validating that internal CL incentives work after multiple epochs with gauge updates
• add functional test validating that CL incentives work after creating multiple external gauges for a single: per pool id, uptime index, incentive denom and incentive creator