InstalledAddonDetailsActivity is only used to display an installed
add-on. getAddons() builds a list of all installed extensions, plus a
list of recommended extensions that may be fetched from the network.
The latter may be a very slow operation, and is unnecessary in this
context.
This introduces a new getAddonByID() method to quickly look up the
latest add-on, which speeds up the rendering of the extension management
view of an installed add-on.
Differential Revision: https://phabricator.services.mozilla.com/D239544
34d7f267f9