[Sketcher] Use knot insertion pointer when using that tool

Icon courtesy @bitacovir, adapted from https://forum.freecadweb.org/viewtopic.php?f=34&t=66262&p=572480#p572471.

src/Mod/Sketcher/Gui/Resources/Sketcher.qrc

@@ -200,6 +200,7 @@
         <file>icons/pointers/Sketcher_Pointer_Create_Point.svg</file>
         <file>icons/pointers/Sketcher_Pointer_Extension.svg</file>
         <file>icons/pointers/Sketcher_Pointer_External.svg</file>
+        <file>icons/pointers/Sketcher_Pointer_InsertKnot.svg</file>
         <file>icons/pointers/Sketcher_Pointer_Oblong.svg</file>
         <file>icons/pointers/Sketcher_Pointer_Regular_Polygon.svg</file>
         <file>icons/pointers/Sketcher_Pointer_Slot.svg</file>

src/Mod/Sketcher/Gui/Resources/icons/pointers/Sketcher_Pointer_InsertKnot.svg

@@ -0,0 +1,79 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   version="1.1"
+   height="64"
+   width="64"
+   id="svg10"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:dc="http://purl.org/dc/elements/1.1/">
+  <title
+     id="title839">Sketcher_PointerInsertKnot</title>
+  <metadata
+     id="metadata16">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title>Sketcher_PointerInsertKnot</dc:title>
+        <dc:date>17-02-2022</dc:date>
+        <dc:creator>
+          <cc:Agent>
+            <dc:title>bitacovir</dc:title>
+          </cc:Agent>
+        </dc:creator>
+        <dc:rights>
+          <cc:Agent>
+            <dc:title>FreeCAD LGPL2+</dc:title>
+          </cc:Agent>
+        </dc:rights>
+        <dc:publisher>
+          <cc:Agent>
+            <dc:title>FreeCAD</dc:title>
+          </cc:Agent>
+        </dc:publisher>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <defs
+     id="defs14" />
+  <g
+     id="symbol"
+     style="fill:none;stroke:#cc0000;stroke-width:2">
+    <path
+       d="M 54.992381,9.9648713 C 63.989736,34.998545 7.0064885,30.993157 14.004432,57.028178"
+       id="path2"
+       style="stroke-width:2.00106;stroke:#dddddd;stroke-opacity:1" />
+    <circle
+       cx="46.915485"
+       cy="27.210726"
+       r="3"
+       id="circle4"
+       style="fill:#cc0000" />
+    <circle
+       id="circle4-8"
+       r="6.8303161"
+       cy="27.138775"
+       cx="46.828571"
+       style="fill:none;stroke:#cc0000;stroke-width:2;stroke-miterlimit:4;stroke-dasharray:none" />
+    <path
+       style="fill:none;stroke:#cc0000;stroke-width:2;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+       d="m 46,38 c 5.985948,0.01349 9.389948,-2.960925 11,-8"
+       id="path860" />
+    <path
+       id="path860-4"
+       d="m 36,28 c -0.01349,-5.985948 2.960925,-9.389948 8,-11"
+       style="fill:none;stroke:#cc0000;stroke-width:2;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1" />
+  </g>
+  <g
+     id="crosshair"
+     style="stroke:#ffffff;stroke-width:2.5;stroke-linecap:round;stroke-linejoin:miter;">
+    <path
+       d="m16,3v9m0,8v9m-13-13h9m8,0h9"
+       id="path7" />
+  </g>
+</svg>