o.c.utility.pvmanager.widgets: Make VTable widget font update w/ zoom

When BOY display is zoomed, it updates the fonts of all widgets.
The VTable widget - a composite - didn't update the fonts of its
internal components, so overall its fonts didn't zoom
Merge pull request #315 from ControlSystemStudio/bug_252

o.c.utility.pvmanager.widgets: Make VTable widget font update w/ zoom: Fixes #252