Sketcher: Improve validation ui to select whether to ignore construction geometry or not

========================================================================================

Users generally expect that validate Sketch checks the visible part, perhaps because it is not called from the sketcher's edit view, but from the 3D view, perhaps
because that part is relevant for further construction.

On the other hand the tool's name is Validate Sketch and construction geometry belongs to the sketch.

So a new checkbox is introduced, by default enabled to ignore construction, but still allowing the user to make it operate in one direction or the other.

See:
https://forum.freecadweb.org/viewtopic.php?f=3&t=26139&p=208582#p208693

src/Mod/Sketcher/Gui/TaskSketcherValidation.cpp

@@ -70,6 +70,7 @@ SketcherValidation::SketcherValidation(Sketcher::SketchObject* Obj, QWidget* par
     ui->fixButton->setEnabled(false);
     ui->fixConstraint->setEnabled(false);
     ui->swapReversed->setEnabled(false);
+    ui->checkBoxIgnoreConstruction->setEnabled(true);
     double tolerances[8] = {
         Precision::Confusion() / 100,
         Precision::Confusion() / 10,
@@ -180,7 +181,7 @@ void SketcherValidation::on_findButton_clicked()
     for (std::size_t i=0; i<geom.size(); i++) {
         Part::Geometry* g = geom[i];
 
-        if(g->Construction)
+        if(g->Construction && ui->checkBoxIgnoreConstruction->isChecked())
             continue;
 
         if (g->getTypeId() == Part::GeomLineSegment::getClassTypeId()) {

src/Mod/Sketcher/Gui/TaskSketcherValidation.ui

@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>242</width>
-    <height>423</height>
+    <width>311</width>
+    <height>453</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -57,7 +57,7 @@
         </property>
        </widget>
       </item>
-      <item row="1" column="1">
+      <item row="2" column="1">
        <widget class="QPushButton" name="fixButton">
         <property name="text">
          <string>Fix</string>
@@ -67,20 +67,30 @@
       <item row="0" column="1">
        <widget class="QComboBox" name="comboBoxTolerance"/>
       </item>
-      <item row="1" column="0">
+      <item row="2" column="0">
        <widget class="QPushButton" name="findButton">
         <property name="text">
          <string>Find</string>
         </property>
        </widget>
       </item>
-      <item row="2" column="0" colspan="2">
+      <item row="3" column="0" colspan="2">
        <widget class="QPushButton" name="highlightButton">
         <property name="text">
          <string>Highlight open vertexes</string>
         </property>
        </widget>
       </item>
+      <item row="1" column="0" colspan="2">
+       <widget class="QCheckBox" name="checkBoxIgnoreConstruction">
+        <property name="text">
+         <string>Ignore construction geometry</string>
+        </property>
+        <property name="checked">
+         <bool>true</bool>
+        </property>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>