New RGB Matrix effect: Single color reactive (#5330)

* Adds new RGB Matrix effect: rgb_matrix_config'd reactive LEDs

* [Docs] Adds disable for new effect

* [Docs] Added new effect to list of effects

quantum/rgb_matrix.h

@@ -110,6 +110,9 @@ enum rgb_matrix_effects {
    #ifndef DISABLE_RGB_MATRIX_SOLID_REACTIVE
        RGB_MATRIX_SOLID_REACTIVE,
    #endif
+   #ifndef DISABLE_RGB_MATRIX_SOLID_REACTIVE_SIMPLE
+       RGB_MATRIX_SOLID_REACTIVE_SIMPLE,
+   #endif
    #ifndef DISABLE_RGB_MATRIX_SPLASH
        RGB_MATRIX_SPLASH,
    #endif