[Wasm] Move external RTT checkers to web.common and reuse in Wasm

#KT-56849

compiler/testData/diagnostics/wasmTests/jsInterop/rtti/checkForNativeInterface.kt

@@ -0,0 +1,6 @@
+// FIR_IDENTICAL
+external interface I
+
+fun box(a: Any, b: Any): Boolean {
+    return <!CANNOT_CHECK_FOR_EXTERNAL_INTERFACE!>a is I<!> && <!CANNOT_CHECK_FOR_EXTERNAL_INTERFACE!>b !is I<!>
+}