As part of the banner redesign project, this commit applies the new
banner styles to the desktop notifications navbar banner.
This commit also acts as a base for the following banner redesign
commits by defining the `banners.ts` module, which now acts as the
centralized module to handle the banner rendering and sets up the
common event listeners.
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.
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