Bug 33813: Masthead lists button requires an aria-label

Bug 33813: Masthead lists button requires an aria-label

This patch adds an aria-label to the Lists button in the masthead. It is currently not descriptive enough and doesn't identify what is displayed when clicking the button.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 7129b772b559c50311bccfa3b9f0402ec1ce1100)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>