GUI: Add missing flags + rework

Added missing flags
Resized to keep a coherent look
Replaced complex flags with simpler versions

default/icons/flags/tr.svg

@@ -1 +1,58 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="1200" height="800"><path fill="#E30A17" d="M0 0h1200v800H0z"/><circle cx="425" cy="400" r="200" fill="#fff"/><circle cx="475" cy="400" r="160" fill="#e30a17"/><path fill="#fff" d="M583.334 400l180.901 58.779-111.804-153.885v190.212l111.804-153.885z"/></svg>
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   width="900"
+   height="600"
+   version="1.1"
+   id="svg10"
+   sodipodi:docname="tr.svg"
+   inkscape:version="1.1.1 (3bf5ae0d25, 2021-09-20)"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <defs
+     id="defs14" />
+  <sodipodi:namedview
+     id="namedview12"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageshadow="2"
+     inkscape:pageopacity="0.0"
+     inkscape:pagecheckerboard="0"
+     showgrid="false"
+     inkscape:snap-page="true"
+     inkscape:zoom="0.44083333"
+     inkscape:cx="370.88847"
+     inkscape:cy="171.26654"
+     inkscape:window-width="1920"
+     inkscape:window-height="1017"
+     inkscape:window-x="-8"
+     inkscape:window-y="-8"
+     inkscape:window-maximized="1"
+     inkscape:current-layer="svg10" />
+  <path
+     fill="#e30a17"
+     d="M 0,0 H 900 V 600 H 0 Z"
+     id="path2"
+     style="stroke-width:0.750001" />
+  <circle
+     cx="318.75"
+     cy="300"
+     r="150.00002"
+     fill="#ffffff"
+     id="circle4"
+     style="stroke-width:0.750001" />
+  <circle
+     cx="356.25"
+     cy="300"
+     r="119.99999"
+     fill="#e30a17"
+     id="circle6"
+     style="stroke-width:0.750001" />
+  <path
+     fill="#ffffff"
+     d="m 437.5005,300 135.67575,44.08426 -83.853,-115.41376 v 142.65901 l 83.853,-115.41376 z"
+     id="path8"
+     style="stroke-width:0.750001" />
+</svg>