Support quotes at the end of a raw string

Fix for KT-4650 Can't use double quote at the end of the raw string

#KT-4650 Fixed

compiler/testData/codegen/box/strings/rawStringsWithManyQuotes.kt

@@ -0,0 +1,28 @@
+class P(val actual: String, val expected: String)
+fun array(vararg s: P) = s
+
+fun box() : String {
+  val data = array(
+    P("""""", ""),
+    P(""""""", "\""),
+    P("""""""", "\"\""),
+    P(""""""""", "\"\"\""),
+    P("""""""""", "\"\"\"\""),
+    P("""" """, "\" "),
+    P(""""" """, "\"\" "),
+    P(""" """", " \""),
+    P(""" """"", " \"\""),
+    P(""" """""", " \"\"\""),
+    P(""" """"""", " \"\"\"\""),
+    P(""" """""""", " \"\"\"\"\""),
+    P("""" """", "\" \""),
+    P(""""" """"", "\"\" \"\"")
+  )
+
+  for (i in 0..data.size-1) {
+    val p = data[i]
+    if (p.actual != p.expected) return "Fail at #$i. actual='${p.actual}', expected='${p.expected}'"
+  }
+
+  return "OK"
+}