Fix Nodes.InterpolatedStringNode translation and set new line flag properly

Author: andrykonchin

spec/truffle/parsing/fixtures/strings/concatenated_literal.yaml

@@ -7,7 +7,7 @@ ast: |
   StringLiteralNode
       attributes:
           encoding = UTF-8
-          flags = 0
+          flags = 1
           sourceCharIndex = 0
           sourceLength = 11
           tstring = foobar

spec/truffle/parsing/fixtures/strings/concatenated_literal_frozen.yaml

@@ -10,7 +10,7 @@ ast: |
   FrozenStringLiteralNode
       attributes:
           definition = "expression" (ASCII-8BIT)
-          flags = 0
+          flags = 1
           frozenString = "foobar" (UTF-8)
           sourceCharIndex = 30
           sourceLength = 11

src/main/java/org/truffleruby/parser/YARPTranslator.java

@@ -2511,7 +2511,18 @@ private static Nodes.StringNode concatStringNodes(Nodes.InterpolatedStringNode n
         var last = ArrayUtils.getLast(parts);
         int length = last.endOffset() - start;
         short flags = node.isFrozen() ? Nodes.StringFlags.FROZEN : NO_FLAGS;
-        return new Nodes.StringNode(flags, concatenated, start, length);
+
+        // Prism may assign a new-line flag to one of the nested parts instead of the outer String node
+        boolean isNewLineFlag = node.hasNewLineFlag();
+        for (var part : parts) {
+            if (part.hasNewLineFlag()) {
+                isNewLineFlag = true;
+            }
+        }
+
+        var stringNode = new Nodes.StringNode(flags, concatenated, start, length);
+        stringNode.setNewLineFlag(isNewLineFlag);
+        return stringNode;
     }
 
     /** Translate parts of interpolated String, Symbol or Regexp */