Add HomeConst.ts documentation

[ggsawatyanon]

Summary

This pull request cleans up the code base by removing a redundant and unused component (CantFindApartmentModal.ts), moves the documentation for DropDown and DropDownWithLabel to above the function declaration for clarity, and adds documentation for HomeConsts.ts.

• Removed CantFindApartmentModal.ts (an unused component)
• Updated DropDown.tsx and DropDownWithLabel.tsx documentation for clarity
• Added documentation for HomeConsts.ts

Test Plan

[dti-github-bot]

[diff-counting] Significant lines: 12.

[CasperL1218]

The documentation for frontend/src/constants/HomeConsts.ts is clear and informative.

One possible change is to update the DropDown component's documentation, which currently does not follow our new documentation guideline. For instance, the current documentation did not provide specification for all four parameters.