[Typescript Conversion: Level 19]: Convert ui/components/ui/menu/menu-item.js to typescript

## **Description**

Convert `ui/components/ui/menu/menu-item.js` from JavaScript to TypeScript as part of the TS migration initiative.

## **Scenario (for user stories only)**

_(Not applicable)_

## **Design (for user stories only)**

_(Not applicable)_

## **Technical Details (for technical tasks only)**

- Convert this file to TypeScript.
- Migration Level: **19**
- Dependencies:
- ui/helpers/constants/design-system.ts
- Dependents:
- ui/components/ui/menu/index.js

## **[Threat Modeling Framework](https://github.com/adamshostack/4QuestionFrame) (for technical tasks only)**

- What are we working on? Convert file to TypeScript.
- What can go wrong? Type errors, integration mismatches, missing types.
- What are we going to do about it? Write types carefully and test thoroughly.
- Did we do a good job? _(To be evaluated)_

## **Acceptance Criteria**

- File is fully converted to TypeScript.
- Tests pass.
- File adheres to linting rules.
- Functionality remains unchanged.

## **Stakeholder Review (for MetaMask employees only)**

- [X] Engineering
- [ ] Design
- [ ] Product
- [ ] QA
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management
- [ ] Other

## **References**

- Parent issue: #31460

Start with ui/components/ui/menu/menu-item.js and review ui/helpers/constants/design-system.ts for the relevant dependency, then check how ui/components/ui/menu/index.js uses the component. Convert the file while preserving functionality, and run the applicable tests and lint checks to confirm the acceptance criteria.

Written by the indexing model from the issue text.