Fix some problems with jsCode function

1. Fix a bug in frontend when passing non-String constant led to exception
2. Fix a bug in backend when passing non-JetStringTeplate string constant led to exception
3. Avoid recomputing constant argument in backend

compiler/testData/diagnostics/testsWithJsStdLib/jsCode/argumentIsLiteral.kt

@@ -6,7 +6,12 @@ fun test() {
     val b = "b"
 
     js(a)
-    js(b)
+    js((b))
+    js(("c"))
+    js(<!CONSTANT_EXPECTED_TYPE_MISMATCH, JSCODE_ARGUMENT_SHOULD_BE_CONSTANT!>3<!>)
+    js(<!TYPE_MISMATCH, JSCODE_ARGUMENT_SHOULD_BE_CONSTANT!>3 + 2<!>)
+    js(<!CONSTANT_EXPECTED_TYPE_MISMATCH, JSCODE_ARGUMENT_SHOULD_BE_CONSTANT!>1.0f<!>)
+    js(<!CONSTANT_EXPECTED_TYPE_MISMATCH, JSCODE_ARGUMENT_SHOULD_BE_CONSTANT!>true<!>)
     js("$a")
     js("${1}")
     js("$b;")