all: replace target=wasi with target=wasip1

This eliminates the 'wasi' build tag in favor of 'GOOS=wasip1', introduced in Go 1.21.

For backwards compatablity, -target=wasi is a synonym for -target=wasip1.

targets/wasip1.json

@@ -2,9 +2,9 @@
 	"llvm-target":   "wasm32-unknown-wasi",
 	"cpu":           "generic",
 	"features":      "+bulk-memory,+mutable-globals,+nontrapping-fptoint,+sign-ext",
-	"build-tags":    ["tinygo.wasm", "wasi"],
-	"goos":          "linux",
-	"goarch":        "arm",
+	"build-tags":    ["tinygo.wasm"],
+	"goos":          "wasip1",
+	"goarch":        "wasm",
 	"linker":        "wasm-ld",
 	"libc":          "wasi-libc",
 	"rtlib":         "compiler-rt",