JS: refactor flat declaration generator. Add more tests on inter-module dependencies

js/js.translator/testData/box/crossModuleRef/topLevelFunction.kt

@@ -0,0 +1,49 @@
+// MODULE: lib
+// FILE: lib.kt
+
+package lib
+
+fun foo() = 23
+
+@native fun bar(): Int = noImpl
+
+inline fun baz() = 99
+
+inline fun callFoo() = foo()
+
+inline fun buzz(): Int {
+    val o = object {
+        fun f() = 111
+    }
+    return o.f()
+}
+
+// FILE: lib.js
+
+function bar() {
+    return 42;
+}
+
+// MODULE: main(lib)
+// FILE: main.kt
+
+package main
+
+fun box(): String {
+    val a = lib.foo()
+    if (a != 23) return "fail: simple function: $a"
+
+    val b = lib.bar()
+    if (b != 42) return "fail: native function: $b"
+
+    val c = lib.baz()
+    if (c != 99) return "fail: inline function: $c"
+
+    val d = lib.buzz()
+    if (d != 111) return "fail: inline function with object expression: $d"
+
+    val e = lib.callFoo()
+    if (e != 23) return "fail: inline function calling another function: $e"
+
+    return "OK"
+}