JS: support SAM conversion

The SAM adapter is generate on declaration site. This is different
from the JVM approach.

`external fun interface` is banned for now.

Reusing interface declaration for the adapter is a hack which
reduces code size and makes importing/exporting the adapter
effortless.

compiler/testData/codegen/box/funInterface/primitiveConversions.kt

@@ -0,0 +1,20 @@
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+
+// IGNORE_BACKEND_FIR: JVM_IR
+// SKIP_DCE_DRIVEN
+
+// This test should check argument coercion between the SAM and the lambda.
+// For now it checks that Char is boxed in JS
+
+fun interface CharToAny {
+    fun invoke(c: Char): Any
+}
+
+fun foo(c: CharToAny): Any = c.invoke('O')
+
+fun box(): String {
+
+    if (foo { it } !is Char) return "fail"
+
+    return "OK"
+}