Add circle slot

[setaman]

Extend the slots to allow users to completely replace rendered circles and paths. This will provide maximum flexibility for the users but also require more responsibility.

Core goals

• Users should have more control over the resulting SVG, enabling them to easily add additional styles and customize the appearance
• Users should be able to provide custom SVG figures, such as an ellipse or a custom path
• The plugin should expose the internal calculations used to determine values like position, radius, circumference, etc., through the slots. This will empower users to directly apply these values to custom SVG elements

Acceptance criteria

• [ ] The plugin exposes scoped slots for progress/empty/fill/loader circle
• [ ] Scoped slots should expose internally calculated values, including position, radius, path, as well as styles, classes, and animation-related properties, that are used to render the default circles

[setaman]

could cover #104