Add Watermark Support for Shaka Player UI

[chafroudtarek]

This feature introduces a watermark functionality to Shaka Player's UI. It allows developers to add static or dynamic watermarks to video playback.

Key Features:

1. Static Watermark:

• Display a fixed watermark on the video player.

• Options for position (e.g., top-right, bottom-left), color, size, and opacity.

2. Dynamic Watermark:

• Adds a moving watermark that changes position periodically.

• Supports customization for text, transition duration, display duration, and alpha blending.

3. Customizable Options:

• Developers can specify text, size, color, and animation intervals.

4. Removal and Cleanup:

• The watermark can be programmatically removed or reset.

• This feature enhances content security by discouraging unauthorized distribution and ensures compliance with branding or licensing requirements.

[avelad]

@chafroudtarek Are you interested in creating a PR to add this feature?