Make Snap `OnClientRequest` to accept `approvalRequestData` and pass it while calling `ApprovalController:addRequest`

### What is this about?

In the send flow, Product wants to display full-page confirmations for non-EVM transaction approvals, similar to how we implemented them for EVM transactions. ([Confirmation task](https://github.com/MetaMask/MetaMask-planning/issues/5708))

Currently, all Snap approvals are presented as modals. To enable full-page confirmations, we need a way to determine whether a `Snap.onClientRequest` originates from the send flow.

The best approach is to use the `requestData` metadata when adding approvals through `ApprovalController.addRequest`. This means we should introduce a generic option to `Snap.onClientRequest` for example, `approvalRequestData` and ensure it’s passed along when creating the approval request.

More context: https://consensys.slack.com/archives/C099HFE1ZHA/p1762175952514429

### Scenario

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### Design

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### Technical Details

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### Threat Modeling Framework

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### Acceptance Criteria

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### 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)

### References

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Start by tracing the Snap.onClientRequest entry point through ApprovalController.addRequest and inspect how request metadata is currently handled. Done means a generic approvalRequestData option can be accepted by Snap.onClientRequest and is passed into the approval request for send-flow confirmation handling.

Written by the indexing model from the issue text.