Implement Stories feature behind flag.

Co-Authored-By: Greyson Parrelli <37311915+greyson-signal@users.noreply.github.com>
Co-Authored-By: Rashad Sookram <95182499+rashad-signal@users.noreply.github.com>

app/src/main/java/org/thoughtcrime/securesms/scribbles/HSVColorSlider.kt

@@ -57,6 +57,11 @@ object HSVColorSlider {
     )
   }.toIntArray()
 
+  @ColorInt
+  fun getLastColor(): Int {
+    return colors.last()
+  }
+
   fun AppCompatSeekBar.getColor(): Int {
     return colors[progress]
   }