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

#KT-56849

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

@@ -0,0 +1,10 @@
+// FIR_IDENTICAL
+external interface I
+
+external interface J
+
+fun box(a: Any) = when (a) {
+    <!CANNOT_CHECK_FOR_EXTERNAL_INTERFACE!>is I<!> -> 0
+    <!CANNOT_CHECK_FOR_EXTERNAL_INTERFACE!>!is J<!> -> 1
+    else -> 2
+}