Split the API activity indicator into its own view.

Review Request #9446 — Created Dec. 15, 2017 and updated — Latest diff uploaded


Review Board


The API activity indicator, which gives users indication that network
communication is occurring, has previously been pretty interwoven with
the rest of the API communication code. This is the first step in
cleaning up that code by moving the display for this indicator into its
own view.

The view manages showing activity and error information, and displays
details on any errors shown, just like the old indicator. However, the
error details box has been simplified, removing the response payload.
That information was more useful back when browsers didn't come with
useful debugging consoles, but is a lot less useful now. Instead of
attempting to show anything, we just say that more details might be
found in the browser and server logs.

Tested Loading/Saving activity indication.

Tested display of errors and error details.