Implement price fetching logic

[ga-reth]

Problem to Solve

When estimating gas and fees for x-chain calls via SolverNet, we'll need to apply conversion rates of estimations in order to charge users appropriately. We need research / design this mechanism keeping in mind this logic will be consumed via the SDK, and therefore we shouldn't simply use our own pricing API calls.

Proposed Solution

TBD based on research uncovered