Update the starlingx-dashboard MANIFEST.in file to specify
inclusion of additional files necessary for adding themes
to the python module wheel, which is used in building the
stx-horizon docker image.
Story: 2004520
Task: 28586
Change-Id: Ie9615c1bd89539f5ea928863f67214c50d0c15b2
Signed-off-by: Don Penney <don.penney@windriver.com>