[ImagePicker] Setup required permissions and manifest configuration

[AkshayAshokCode]

Ensure the library works seamlessly by documenting and optionally enforcing required manifest declarations, permissions, and provider configurations for image capture and file handling.
Tasks:
Add CAMERA permission to manifest if camera source is used
Add declaration with FileProvider for temp image capture
Generate or document required res/xml/file_paths.xml
Provide a helper or documentation snippet to simplify setup for consuming apps
(Optional) Add runtime permission check for camera (if needed)
Ensure fallback behavior or error callback if setup is incomplete
Update README with manifest and setup steps