[Wasm] Support WASI target in K2

- Support WASI mode in CLI and test infrastructure
- Add external declaration checker
- Split Fir diagnostic lists into Base, JS and WASI

#KT-56849 Fixed

js/js.frontend/src/org/jetbrains/kotlin/js/config/WasmTarget.kt

@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.js.config
 
+import org.jetbrains.kotlin.config.CompilerConfiguration
+
 enum class WasmTarget {
     JS,
     WASI;
@@ -16,4 +18,7 @@ enum class WasmTarget {
             else -> null
         }
     }
-}
+}
+
+val CompilerConfiguration.wasmTarget: WasmTarget
+    get() = get(JSConfigurationKeys.WASM_TARGET, /* defaultValue = */ WasmTarget.JS)