ActivityIndicator upgrade

[azizbecha]

Is your feature request related to a problem? Please describe.
`ActivityIndicator is limited in customization and naming compared to modern UI needs.

Describe the solution you'd like

• Rename ActivityIndicator to Spinner
• Add more spinner variants

Describe alternatives you've considered
Using custom loaders or third-party spinner libraries.

Additional context
A Spinner component with multiple variants would improve flexibility and align better with Paper theme.

[vamos-23]

Hi, I’d like to work on this.

Instead of renaming the component (which may introduce breaking changes), I propose starting with a smaller improvement.

Understanding:
The current ActivityIndicator has limited customization compared to modern UI expectations.

Approach:
I plan to enhance its flexibility by improving existing props (such as size and color consistency) and ensuring better alignment with theme usage, without introducing breaking changes.

If this approach sounds good, I can start with this improvement.