Completely rewrote logic for custom widgets and add new "Frosted-Glass" design

BREAKING CHANGES:

• Removed hardcoded WhatsApp design.
• Rewritten entire logic of customWidgets.
• Moved initialColor and initialStrokeWidth from paintEditorConfigs to imageEditorTheme-paintingEditor.

Features:

• Added new design Frosted-Glass.
• WhatsApp theme is now fully editable.
• Smaller build size and minimal performance boost due to removal of hardcoded WhatsApp design.
• Simplified usage of customWidgets.
• Editor design is now more customizable.