Added ad-hoc KtValueArgument.stringTemplateExpression

Use only stub stringTemplateExpression if it is present and don't use ast nodes as it could be unbounded

#KT-47034 Fixed

compiler/psi/src/org/jetbrains/kotlin/psi/KtValueArgument.java

@@ -59,6 +59,10 @@ public class KtValueArgument extends KtElementImplStub<KotlinValueArgumentStub<?
             KtStubElementTypes.STRING_TEMPLATE
     );
 
+    private static final TokenSet STRING_TEMPLATE_EXPRESSIONS_TYPES = TokenSet.create(
+            KtStubElementTypes.STRING_TEMPLATE
+    );
+
     @Override
     @Nullable @IfNotParsed
     public KtExpression getArgumentExpression() {
@@ -73,6 +77,19 @@ public class KtValueArgument extends KtElementImplStub<KotlinValueArgumentStub<?
         return findChildByClass(KtExpression.class);
     }
 
+    @Nullable
+    public KtStringTemplateExpression getStringTemplateExpression() {
+        KotlinPlaceHolderStub<? extends KtValueArgument> stub = getStub();
+        KtExpression expression;
+        if (stub != null) {
+            KtExpression[] stringTemplateExpressions = stub.getChildrenByType(STRING_TEMPLATE_EXPRESSIONS_TYPES, KtExpression.EMPTY_ARRAY);
+            expression = stringTemplateExpressions.length != 0 ? stringTemplateExpressions[0] : null;
+        } else {
+            expression = findChildByClass(KtExpression.class);
+        }
+        return expression instanceof KtStringTemplateExpression ? (KtStringTemplateExpression)expression : null;
+    }
+
     @Override
     @Nullable
     public KtValueArgumentName getArgumentName() {