feat: add various system and theme icons, configuration files, and support assets

squashfs-root/usr/share/icons/Humanity-Dark/status/22/indicator-messages.svg

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+<svg id="svg2" width="22" height="22" version="1.0" xmlns="http://www.w3.org/2000/svg">
+ <g id="g2829">
+  <rect id="rect3170" x="2.5" y="5.4995" width="17" height="11" style="fill:none;stroke-linecap:square;stroke:#969696"/>
+  <path id="path3172" d="m4.5 7.5 6 6h1l6-6" style="fill:none;stroke-width:1px;stroke:#969696"/>
+  <path id="path3174" d="m4.5 14.5 3.5-3.5" style="fill:none;stroke-width:1px;stroke:#969696"/>
+  <path id="path3176" d="m17.5 14.5-3.5-3.5" style="fill:none;stroke-width:1px;stroke:#969696"/>
+ </g>
+</svg>