Spinner/loader

[wojtekmaj]

Is your feature request related to a problem? Please describe.

Certain UI elements must load asynchronously, or need to end for a background process to finish.

Describe the solution you'd like

Provide a standardized spinner/loader/progress component that:

• Supports determinate and indeterminate progress
• Supports circular and linear variant
• Can optionally display a label underneath like "Connecting…" or "Loading…"
• Provides feedback for users using assistive technologies

Describe alternatives you've considered

Custom built component. Nothing against that, but I feel it's a pattern common enough to consider including in GEL.

Additional context