compiler, runtime: enable go:wasmexport for wasip2 (#4499)

* compiler: prefer go:wasmexport over go:export

* runtime, targets/wasip2: enable -buildmode=c-shared for wasip2

* runtime: rename import from wasi_run to wasiclirun (PR feedback)

targets/wasip2.json

@@ -3,6 +3,7 @@
 	"cpu":           "generic",
 	"features":      "+bulk-memory,+mutable-globals,+nontrapping-fptoint,+sign-ext",
 	"build-tags":    ["tinygo.wasm", "wasip2"],
+	"buildmode":     "c-shared",
 	"goos":          "linux",
 	"goarch":        "arm",
 	"linker":        "wasm-ld",