Introduce Kotlin language substitutor to fix exceptions in velocity files

Related to KT-31470 (should fix the problem or at least soften it)
May be related also to KT-30977
#KT-30886 Fixed

idea/resources/META-INF/plugin-common.xml

@@ -863,6 +863,8 @@
 
     <orderEnumerationHandlerFactory implementation="org.jetbrains.kotlin.idea.roots.KotlinNonJvmOrderEnumerationHandler$Factory"/>
 
+    <lang.substitutor language="kotlin" order="last" implementationClass="org.jetbrains.kotlin.idea.KotlinLanguageSubstitutor"/>
+
     <intentionAction>
       <className>org.jetbrains.kotlin.idea.intentions.FoldInitializerAndIfToElvisIntention</className>
       <category>Kotlin</category>