Add space before 'where' keyword

#KT-19213 Fixed

idea/formatter/src/org/jetbrains/kotlin/idea/formatter/kotlinSpacingRules.kt

@@ -319,6 +319,7 @@ fun createSpacingBuilder(settings: CodeStyleSettings, builderUtil: KotlinSpacing
             betweenInside(IDENTIFIER, PROPERTY_DELEGATE, PROPERTY).spaces(1)
 
             before(INDICES).spaces(0)
+            before(WHERE_KEYWORD).spaces(1)
         }
         custom {
 

idea/testData/formatter/WhereClause.after.kt

@@ -10,3 +10,7 @@ fun <T> foo()
         where T : NavigationItem,
               T : RustNamedElement {
 }
+
+interface Bound1
+interface Bound2
+class WhereClass1<T> where T : Bound1, T : Bound2

idea/testData/formatter/WhereClause.kt

@@ -10,3 +10,7 @@ fun <T> foo()
 where T : NavigationItem,
 T : RustNamedElement {
 }
+
+interface Bound1
+interface Bound2
+class WhereClass1<T>where T : Bound1, T : Bound2