Support cancel and speed up transactions in the institutional snap

### What is this about?

[ECA-3](https://consensys-vertical-apps.github.io/ethereum-custodian-api/) supports replacing transactions (same nonce, higher gas) in order to cancel (no-op) or speed up (just boost gas) them.

However there is no mechanism to trigger this within MetaMask.

### Acceptance Criteria

- Support cancelling tranactions, before or after they enter the mempool
- Support speeding up transactions
- Use `custodian_createTransaction`

### Stakeholder review needed before the work gets merged

- [ ] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)