Fix Loading component timeout

[WiXSL]

Problem

Loading component is difficult to re-use because it has a hard-coded one second timeout inside of it.

Solution

Add a timeout prop default to one second to make it more flexible

Additional Checks

• The PR targets master for a bugfix or a documentation fix, or next for a feature
• The PR includes unit tests (if not possible, describe why)
• The PR includes one or several stories (if not possible, describe why)
• The documentation is up to date

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[fzaninotto]

Thanks!

This is technically an evolution, though. Would you mind rebasing your PR on next?