Stick to function naming conventions in OutputDevice

Function name changes for consistency in OutputDevice:
* impPaintLineGeometryWithEvtlExpand ->
       ImplPaintLineGeometryWithEvtlExpand
* ImpDrawPolyPolygonWithB2DPolyPolygon ->
       ImplDrawPolyPolygonWithB2DPolyPolygon
* ImpTryDrawPolyLineDirect    -> ImplTryDrawPolyLineDirect
* ImpDrawPolyLineWithLineInfo -> ImplDrawPolyLineWithLineInfo

Change-Id: Iae1ce07036856902259cef0a05afb57fd657325e
Reviewed-on: https://gerrit.libreoffice.org/8509
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>