Redo profile stack picture in SVG

This way it can be edited easily (for which we needed the DrawIO image) as well as directly shown in the documentation (for which we needed the PNG render).

docs/Profile Stack.drawio

@@ -1 +0,0 @@
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docs/resources/machine_instance.svg

@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<svg xmlns="http://www.w3.org/2000/svg" width="700" height="1010">
+    <defs>
+        <path id="stack-header" d="m0,50 v-30 a20,20 0 0 1 20,-20 h260 a20,20 0 0 1 20,20 v30 z" />
+        <marker id="arrow" refX="2" refY="1.5" markerWidth="3" markerHeight="3" orient="auto-start-reverse">
+            <polygon points="0,0 3,1.5 0,3" />
+        </marker>
+    </defs>
+
+    <g stroke="black" stroke-width="5" fill="silver"> <!-- Stack headers. -->
+        <use href="#stack-header" x="200" y="555" />
+        <use href="#stack-header" x="5" y="5" />
+        <use href="#stack-header" x="395" y="5" />
+    </g>
+    <g stroke="black" stroke-width="10" fill="none"> <!-- Stack outlines. -->
+        <rect x="200" y="555" width="300" height="450" rx="20" /> <!-- Global stack. -->
+        <rect x="5" y="5" width="300" height="450" rx="20" /> <!-- Left extruder. -->
+        <rect x="395" y="5" width="300" height="450" rx="20" /> <!-- Right extruder. -->
+    </g>
+    <g font-family="sans-serif" font-size="25" dominant-baseline="middle" text-anchor="middle">
+        <text x="350" y="582.5">Global stack</text> <!-- Slightly lowered since the top line is thicker than the bottom. -->
+        <text x="350" y="630">User</text>
+        <text x="350" y="680">Custom</text>
+        <text x="350" y="730">Intent</text>
+        <text x="350" y="780">Quality</text>
+        <text x="350" y="830">Material</text>
+        <text x="350" y="880">Variant</text>
+        <text x="350" y="930">Definition changes</text>
+        <text x="350" y="980">Printer</text>
+
+        <text x="155" y="32.5">Left extruder</text> <!-- Slightly lowered again. -->
+        <text x="155" y="80">User</text>
+        <text x="155" y="130">Custom</text>
+        <text x="155" y="180">Intent</text>
+        <text x="155" y="230">Quality</text>
+        <text x="155" y="280">Material</text>
+        <text x="155" y="330">Nozzle</text>
+        <text x="155" y="380">Definition changes</text>
+        <text x="155" y="430">Extruder</text>
+
+        <text x="545" y="32.5">Right extruder</text> <!-- Slightly lowered again. -->
+        <text x="545" y="80">User</text>
+        <text x="545" y="130">Custom</text>
+        <text x="545" y="180">Intent</text>
+        <text x="545" y="230">Quality</text>
+        <text x="545" y="280">Material</text>
+        <text x="545" y="330">Nozzle</text>
+        <text x="545" y="380">Definition changes</text>
+        <text x="545" y="430">Extruder</text>
+    </g>
+    <g stroke="black" stroke-width="5" marker-end="url(#arrow)"> <!-- Arrows. -->
+        <line x1="155" y1="455" x2="345" y2="545" />
+        <line x1="545" y1="455" x2="355" y2="545" />
+    </g>
+</svg>