renderer: added new customization options to the blur shaders (#3650)

Adds to `decoration:blur:` `vibrancy` and `vibrancy_darkness`

src/render/OpenGL.hpp

@@ -64,6 +64,7 @@ struct SMonitorRenderData {
     CShader m_shEXT;
     CShader m_shBLUR1;
     CShader m_shBLUR2;
+    CShader m_shBLURPREPARE;
     CShader m_shBLURFINISH;
     CShader m_shSHADOW;
     CShader m_shBORDER1;