Replace nav bar assets from png to vector drawables (1/2)

Unifying the assets between aosp and pixel while replacing all the image
files per density/orientation with singular xml vector files to simplify
the assets. In addition added a shadow/rotation class to allow these
drawables to be rotated and have a shadow to avoid multiple images of
the same shape in different orientations. Therefore there are a lot of
images deleted replaced by a couple of xml file.

Fixes: 79610337
Fixes: 77731348
Fixes: 65692723
Test: manual
Change-Id: I3fbe2bada815bb98e5ab7e2733f7794054ff649f