feature(unlock-app): Foundational support for wallet funding feature

[0xTxbi]

Description

This PR introduces foundational changes for the new wallet funding feature, enabling users to fund their wallet directly from the settings. It also displays the user's current balance and shows the USD equivalent for clarity.

ScreenGrab

Issues

Fixes # Refs #

Checklist:

• [x] 1 PR, 1 purpose: my Pull Request applies to a single purpose
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have updated the docs to reflect my changes if applicable
• [ ] I have added tests (and stories for frontend components) that prove my fix is effective or that my feature works
• [x] I have performed a self-review of my own code
• [x] If my code involves visual changes, I am adding applicable screenshots to this thread

[0xTxbi]

Please use our existing API to get $

sure thing!