feat: load the user's mpv.conf

src/settings/qtpotatosettings.kcfg

@@ -3,6 +3,12 @@
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.kde.org/standards/kcfg/1.0 http://www.kde.org/standards/kcfg/1.0/kcfg.xsd">
   <kcfgfile name="qtpotatorc"/>
+  <group name="Player">
+    <entry name="LoadMpvConfig" type="Bool">
+      <label>Load the user's mpv.conf when the player starts</label>
+      <default>true</default>
+    </entry>
+  </group>
   <group name="Subtitles">
     <entry name="SubtitleFontSize" type="Int">
       <label>Font size of plain-text and translated subtitles, in mpv's scaled pixels (mpv's own default is 38)</label>