Create Spinner Component

[afonsobspinto]

Basic behavior of the component to be created should allow:

• Work as an overlay
• Work in full-screen
• Content is centered both horizontally and vertically
• Default background is as current

The spinner shows as one of the material ui spinners available: https://material-ui.com/components/progress/

• <Spinner active="true" /> shows a CircularProgress in primary color
• <Spinner active="false" /> hides the spinner
• <Spinner active="true" messages={["Message"]} /> adds a message below the CircularProgress (mockup needed)
• <Spinner active="true" messages={["Message1", "Message2" ]} /> alternates the 2 messages
• <Spinner active="true" elapsed={0.1} /> shows a linear determinate at 10%
• <Spinner active="true" backgroundStyle={{ color: black; opacity: 0.5}} /> changes the overlay background style
• <Spinner active="true" >My content</Spinner> sets an alternative content to the spinner (nothing else is shown inside the spinner)
  To Do:
• <Spinner active="true" fullscreen={True} /> makes the spinner fill the fullscreen or just the parent container.
• Change from Data Viewers to Navigation
• Add className props to change typography c.lassName.

[filippomc]

@afonsobspinto I'm leaving issues open until we include the feature in a release