SVGHMI: intermediate commit while working on dropdown widget.

Here is the plan :
HMI:DropDown : svg:g of svg:rect + svg:text
rect is extended to match content size, and if content size exceed page size, user can scroll
HMI:List : either HMI:List:ListName as svg:text, one tspan per list entry
or HMI:List:ListName:Foreach:HMI_CLASS:SUB/PATH/TO/VALUE@/ROOT/PATH as empty svg:g

<?xml version='1.0' encoding='utf-8'?>
<BeremizRoot URI_location="LOCAL://">
  <TargetType/>
  <Libraries Enable_Python_Library="true"/>
</BeremizRoot>