Add elevation to workFAB to create a shadow

Unable to use md.sys.elevation.level3 but codesearched and
looked it up that this is equivalent to 6dp.

bug: 375597648
Test:
before: https://drive.google.com/file/d/1fp2l5p4wW2Gf3duC2qQ_brQ-xY0bTnOF/view?usp=sharing
after: https://drive.google.com/file/d/19xSAnWJURuwrjhMiywfjNT2vD0G2GoFP/view?usp=sharing
Flag: NONE adding elevation
Change-Id: I484609b4dc817b6d76701f60da51c3ec89bc8755