FIR JS: add K2 variants of all other JS tests

except tests that are not possible to add without some modifications in
the test infra. See todos on the commented-out test declarations

compiler/testData/codegen/box/compileKotlinAgainstKotlin/optionalAnnotation.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND_K2: JVM_IR
+// IGNORE_BACKEND_K2: JVM_IR, JS_IR
 // FIR status: expect/actual in the same module (ACTUAL_WITHOUT_EXPECT)
 // !LANGUAGE: +MultiPlatformProjects
 // !OPT_IN: kotlin.ExperimentalMultiplatform