Jhilliard/loadtest eip 1559 fixes

[praetoriansentry]

Description

There are a few changes here that need to be tested and reviewed carefully:

• Adding a new param, gas-price-multiplier which would allow the gas price to scaled
• Fixing a panic when loadTestResults is empty
• Refactoring to use configureTransactOpts everywhere and to read the suggested gas price from within that function only
• Adding a new metric to the load test output that shows when the tester stopped sending requests
• Switching from uniswapv3.Swapper to tokens.ERC20 in the pool / swap setting. The original token was not mintable which made reusing it very complicated
• Adding some optimizations to speed up uniswapv3 mode when the contracts are already deployed
• Adding some logs to help with using pre-deployed contracts

[leovct]

lgtm!!