Polish workFAB with updated spec.

Updating the workFAB to the new spec: https://docs.google.com/presentation/d/1tTODboxGqJ3ypEyYnr0-bUpSXcvX1cl6Sj8y0Nut5hU/edit?resourcekey=0-9GT8EJG43kTT4aKPWVWRig#slide=id.g2c8f3ae8e02_0_0
Have the background endPadding to be 4 and icon have an endMargin of 12 and the text endMargin of 16.
So that when the text is disappeared, the space between the icon and the right bound is 16dp to spec.

bug:332761814
Test manually:
after LTR expanded:https://drive.google.com/file/d/1NZQW0CF9VFZBoM3673LFiUknqW2nf4r8/view?usp=sharing
after LTR collapsed: https://drive.google.com/file/d/1NRpdTuYQntSs5-yeRL1fJIJy2ETDOYLM/view?usp=sharing
after RTL collapsed: https://drive.google.com/file/d/1NE51MIsS5Fk0DwAuzCehEQzTa42OGj_o/view?usp=sharing
after RTL expanded: https://drive.google.com/file/d/1NPgiPfzw3DOa_xbB_TtlwK-G1Y5WCi53/view?usp=sharing
Flag:None

Change-Id: Ied2efcf6b1bd19c191d80e47bae4f8f6e3794803