feat: add ability to use custom fonts in all apps

[naveensingh]

Type of change(s)

• Bug fix
• Feature / enhancement
• Infrastructure / tooling (CI, build, deps, tests)
• Documentation

What changed and why

• Added font preferences, FontHelper object for custom font management
• Added an inflator factory in base activity that applies the custom font on inflation
• Updated most custom views to use the selected custom font on creation
• Added custom Typography for compose that is the same as the default but with custom fonts applied
• Updated popup menu related styles so proper color and fonts are used
• Updated customization-related strings
  • Color customization ➜ Look & feel
  • Customize colors ➜ Customize appearance
  • Theme and colors ➜ Theme & colors
  • Theme ➜ App theme
  • Apply colors to all Fossify apps ➜ Apply theme to all Fossify apps

This mostly works, but some per-app repo changes are required. Why this is being added is mentioned in FossifyOrg/General-Discussion#323, but honestly, I just wanted custom fonts 😁

Tests performed

• Tested font change in all apps
• Tested font & theme sync with the Fossify Thank You app

Before & after preview

Closes the following issue(s)

• Closes Ability to add custom font General-Discussion#323

Checklist

• I read the contribution guidelines.
• I manually tested my changes on device/emulator (if applicable).
• I updated the "Unreleased" section in CHANGELOG.md (if applicable).
• I have self-reviewed my pull request (no typos, formatting errors, etc.).
• All checks are passing.