feat: add externalLinkClicked to TransactionMetaBase type (#3828)

## Explanation

This prop is used to pass a value used to be added as a transaction
metametric fragment prop.

## References

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Fixes MetaMask/MetaMask-planning#1756
Related to MetaMask/metamask-extension#22631

## Changelog

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### `@metamask/transaction-controller`

- **feat**: Adds `externalLinkClicked` prop to TransactionMetaBase type

## 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 highlighted breaking changes using the "BREAKING" category
above as appropriate

packages/transaction-controller/src/types.ts

@@ -163,6 +163,11 @@ type TransactionMetaBase = {
    */
   estimateUsed?: string;
 
+  /**
+   * Description of the link clicked associated with the transaction
+   */
+  externalLinkClicked?: string;
+
   /**
    * The chosen amount which will be the same as the originally proposed token
    * amount if the user does not edit the  amount or will be a custom token