HIP-1261 Integrate fee calculation library

[steven-sheehy]

Problem

With the release of consensus node v0.68, a library should be available to use to calculate fees for getFeeEstimate.

Solution

• Add library
• Add FeeEstimateResponse NetworkService.estimateFee(FeeEstimateQuery)
• Don't use reactive in service layer
• Use CN lib to produce a FeeEstimateResponse

Alternatives

No response