feat: add vaapi path for video wallpapers on generic gpus

Plugins/ZShell/Wallpaper/shaders/wallpaper.frag

@@ -0,0 +1,11 @@
+uniform sampler2D source;
+uniform vec2 size;
+uniform vec4 crop;
+uniform float alpha;
+out vec4 outColor;
+
+void main() {
+	vec2 p = vec2(gl_FragCoord.x, size.y - gl_FragCoord.y) / size;
+	vec4 c = texture(source, crop.xy + p * crop.zw);
+	outColor = vec4(c.rgb, c.a * alpha);
+}