Fix for width issue of TabSheet (#12805)

Width of v-tabsheet-tabcontainer was set by copying the width
from the ComponentConnector. This produced an incorrect result
when a relative width (other than 100%) was used. Fixed by
assigning the width to 100% when the TabSheet has a defined
width.

Change-Id: I7f128f87406e6e00ceda9ee6e75dcc5539e283b6