This commit replaces the spectrum color picker used in the stream
popover and stream settings with a custom color picker popover, which
contains a grid of predefined color swatches and a custom color option.
The custom color option uses the HTML5 <input type="color"> which shows
the native browser color picker UI.
Fixes#14961.
This directory contains scripts that are used in building, managing,
testing, and other forms of work in a Zulip development environment.
Note that tools that are also useful in production belong in
scripts/ or should be Django management commands.