Add test case for string literals in switch statements in Yul

test/libsolidity/syntaxTests/inlineAssembly/string_literal_switch_case.yul

@@ -0,0 +1,9 @@
+contract C {
+  function f() public pure {
+    assembly {
+      switch codesize()
+      case "1" {}
+      case "2" {}
+    }
+  }
+}

test/libyul/yulSyntaxTests/string_literal_switch_case.yul

@@ -0,0 +1,5 @@
+{
+    switch codesize()
+    case "1" {}
+    case "2" {}
+}