feat: gas station support for relay source transactions

[matthewwalsh0]

Explanation

Use gas fee tokens for deposit transactions in Relay strategy, if native balance is insufficient for max fee.

References

Related to #6150

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed, highlighting breaking changes as necessary
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes

---

Note

Enables using a gas fee token for Relay source network fees when native balance is insufficient, propagating through quotes, totals, and submission.

• Relay strategy (quotes):
  • Compute source network fee using gas fee token if native balance < max fee; add fees.isSourceGasFeeToken and use TransactionController:getGasFeeTokens to match source token, including batch estimation and normalized value.
  • Keep native-fee path as fallback; total gas across multiple txs; fallback gas when missing.
• Submission:
  • Pass gasFeeToken to addTransaction/addTransactionBatch when fees.isSourceGasFeeToken is true.
• Utils:
  • Add calculateGasFeeTokenCost and use it in source-fee calculation; refactor transaction gas fee token cost path.
• Types/Totals:
  • Extend TransactionPayFees and TransactionPayTotals with optional isSourceGasFeeToken.
• Tests/Mocks/Docs:
  • Update tests and messenger mock to cover gas fee token flow; update CHANGELOG.

^{Written by Cursor Bugbot for commit 6407120. This will update automatically on new commits. Configure here.}

[matthewwalsh0]

@metamaskbot publish-preview