EXPERIMENTAL: Add a utility for running async visual tasks

[azangru]

Description

This PR adds a utility for wrapping potentially long-running functions such that:

• if the function completes quickly, nothing additional happens
• if the function takes a while to complete, the wrapper utility sends a signal for showing a loading indicator
• the wrapper utility will take some (configurable) time before sending a new signal to remove the loading indicator, thus avoiding the undesirable flickering of the loading indicator caused by too brief a time of showing it

This utility function can then be used to create a hook that can be used in individual components that display loading spinners (e.g. in the LoadingButton component); or to send signals to the redux store.

[imransl]

@azangru Went through this and like this approach. Can we use this for loading the genome browser as well?