feat(optimized_transaction): Add Priority Fee Cap

[0xIchigo]

This PR allows users to cap the priority fees for a given smart transaction at a specific number and use that as the maximum possible value instead of using what is strictly returned by the Priority Fee API

Consider the following scenarios where we cap priority fees at 10k:

• If the priority fee estimate based on the serialized transaction is 5k, then we'd use 5k
• If the priority fee estimate based on the serialized transaction is 10k, then we'd use 10k
• If the priority fee estimate based on the serialized transaction is 15k, then we'd use 10k

This also resolves #81