CLI-624: move alerts out of tab navigation into to settings

[mike-dydx]

Links (dYdX Internal Use Only)

Linear Ticket: CLI-624: move alerts out of tab navigation into to settings

Figma Design: https://www.figma.com/design/mKevZOfE9nj6MZpiolKYW1/dYdX-%E2%80%BA-Mobile?node-id=9615-982&t=QjiTEfHMhHzJgIrk-4

Description / Intuition

• moves in-app alerts to settings L2 screen
• removes news from alerts/news screen (also some renaming to reflect non-news behavior)
• moves earn/vaults tab to L1 tab navigation screen
• earn/vaults tab icon replaces news/alerts icon
• fixes issue where tab bar gradient flashes a color when app theme changes

Before/After Screenshots or Videos

Desc	After
hidden - flag off
showing - flag on
smaller device
new alerts screen without news
L1 vaults screen
light/dark mode switching and tab bar scroll behind

Type of Change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Refactoring or Technical Debt
• [ ] Documentation update
• [ ] Other (please describe: )

[linear[bot]]

CLI-624 move alerts out of tab navigation into to settings

[ruixhuang]

The vault tab icon doesn't look like the same size as other tab icons. I think we should increase its size. Also, the icon looks like a "close" button.