Feat/polish and propagate

[NewtonMutugi]

This pull request introduces a new reusable Divider component and updates the visual style of the About and Sponsors pages for a more consistent and modern appearance. The main improvements include replacing a static image with the new divider, updating background images and colors, and making minor color adjustments for better visual hierarchy.

Component addition:

• Added a new Divider component in components/shared/Divider.tsx to provide a stylized horizontal divider with gradient and mask effects for reuse across pages.

Visual and style updates (About page):

• Replaced the static divider image with the new Divider component in the About page, improving maintainability and design consistency.
• Updated the About page's background image to droidcon_about_bg.svg for a refreshed look.
• Changed the About page section background from bg-lighter to bg-white for a cleaner appearance.

Visual and style updates (Sponsors page):

• Changed the Sponsors page section background from bg-lighter to bg-white for improved consistency with the About page.
• Updated the background color of the "Build relationships" value card from bg-secondary to bg-primary for better visual hierarchy.Make sure the checklist below is checked before PR merge, mark if not applicable

Issue(s) affected?

Refs #23