Draft: ShapeString: use an actual font file as default, allow TTC files

* To help novice users supply an actual font file from the OS as the default for ShapeStringFontFile.
* The Draft code blocked the use of TTC font files. `Part.makeWireString()` can however handle them (although only the first font in the file can be used).

Additonally:
In a previous PR the bottom spacer was removed from the task panel. This PR brings it back as it is required in some cases. Without it  the "..." button of the file selector can become huge.

src/Mod/Draft/Resources/ui/TaskShapeString.ui

@@ -149,7 +149,7 @@ Uncheck to use working plane coordinate system</string>
           </property>
          </widget>
         </item>
-       <item row="0" column="1">
+        <item row="0" column="1">
          <widget class="QLineEdit" name="leText">
           <property name="toolTip">
            <string>Text to be made into ShapeString</string>
@@ -166,12 +166,19 @@ Uncheck to use working plane coordinate system</string>
         <item row="1" column="1">
          <widget class="Gui::FileChooser" name="fcFontFile">
           <property name="filter">
-           <string>Font files (*.ttf *.otf *.pfb *.TTF *.OTF *.PFB)</string>
+           <string>Font files (*.ttc *.ttf *.otf *.pfb *.TTC *.TTF *.OTF *.PFB)</string>
           </property>
          </widget>
         </item>
        </layout>
       </item>
+      <item row="2" column="0">
+       <spacer name="verticalSpacer_1">
+        <property name="orientation">
+         <enum>Qt::Vertical</enum>
+        </property>
+       </spacer>
+      </item>
      </layout>
     </widget>
    </item>