Refactor

[mikhailChelbaev]

This PR introduces improvements to the library's style and configuration, aligning it with the latest Figma designs and enhancing usability and maintainability. Below are the key updates:

1. Palette Updates:

   • Added new colors to the Palette based on Figma updates: content1, content2, content3, content4.
   • Removed the Secondary component color.
   • Added a new backgroundColor parameter to the ComponentColor struct, which can be utilized for components with a light style.

2. Font Configuration:

   • Instead of 3 sizes, the library now supports 4 semantic font sets, each with 3 sizes.

3. Component Styling:

   • Replaced hardcoded colors in components with colors from the updated Palette.
   • Updated the default color for the Button component.

4. Color Extensions:

   • Replaced Palette extensions with UniversalColor extensions.

5. Preview Helpers:

   • Updated preview helpers by replacing FontPicker with more specific options: HeadlineFontPicker, BodyFontPicker, ButtonFontPicker, and CaptionFontPicker.

6. Countdown Component:

   • Updated the Countdown component model by replacing the font parameter with mainFont and secondaryFont.
   • Introduced other minor improvements to this component.

7. Project Organization:

   • Regrouped files and folders for better project structure and clarity.

8. Documentation:

   • Updated the README to reflect the latest changes.
   • Added missing documentation for the new features and updates.