[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

compiler/testData/diagnostics/wasmWasiTests/external.kt

@@ -0,0 +1,11 @@
+// FIR_IDENTICAL
+import kotlin.wasm.WasmImport
+
+<!WASI_EXTERNAL_FUNCTION_WITHOUT_IMPORT!>external fun foo(): Int<!>
+
+external interface I {
+    <!WASI_EXTERNAL_NOT_TOP_LEVEL_FUNCTION!>fun foo(): Int<!>
+}
+
+@WasmImport("a", "b")
+external fun importedFoo(): Int