Is it still necessary to include FeeCalculator in BlockHashQueue

[tao-stones]

Problem

When working on a separate issue, I noticed blockhash_queue.fee_calculator.lamports_per_signature was used, but perhaps shouldn't be?

Blockhash_queue includes FeeCalculator here.

But FeeCalculator seems pretty much be replaced by FeeStructure.

Proposed Solution

can FeeCalculator be removed to reduce confusion?