feat: know script path

Author: fzyzcjy

frb_internal

@@ -1,2 +1,4 @@
 #!/usr/bin/env bash
-cd tools/frb_internal && exec dart run flutter_rust_bridge_internal "$@"
+SCRIPT=$(readlink -f "$0")
+SCRIPT_PATH=$(dirname "$SCRIPT")
+cd "$SCRIPT_PATH"/tools/frb_internal && exec dart run flutter_rust_bridge_internal "$@"