Feature - Validate the coordinator proposed stacks fees

1. Description

There is nothing preventing a coordinator from proposing large fees for Stacks transactions. This ticket is to fix that by validating fees.

2. Technical Details:

For the initial implementation of fee validation, we should aim to ensure that the proposed fee is under some maximum. Later we can add something fancier for fee estimation, such as having everyone submit their vote on the fee and having the coordinator propose the median or something like that.

2.1 Acceptance Criteria:

• Unreasonably large Stacks fees are rejected by the signers.

3. Related Issues and Pull Requests (optional):