Bug 27496: Accessibility: Navigation buttons are poorly described by screen readers

Bug 27496: Accessibility: Navigation buttons are poorly described by screen readers

    This patch adds aria-haspopup and aria-expanded attributes to the language
    and welcome user buttons so that screen readers will know that they cause a
    popup menu to be displayed.

    To test:
    1. Use an installation with at least 2 active languages
    2. Log in the OPAC
    3. Use a screen reader (e.g. ChromeVox in Chrome) and use the tab key to
       navigate to the language and welcome user buttons while noticing that
       they are described as "Button collapsed" and "Button", respectively
    4. Alternatively, inspect the buttons and notice that they are missing
       aria-haspopup and aria-expanded attributes
    5. Apply the patch
    6. Observe that these buttons now are described as "Popup button collapsed"
       or that they contain the aria-haspopup and aria-expanded attributes like
       the lists button
    7. Sign off

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit e0007bf3623a6e58091eb233c95610761ac33a9e)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>