wasi-common: export StringArray type (#6244)

reusable elsewhere: @mtr is gonna use it in wasi-nn.

crates/wasi-common/src/lib.rs

@@ -69,5 +69,5 @@ pub use dir::WasiDir;
 pub use error::{Error, ErrorExt, I32Exit};
 pub use file::WasiFile;
 pub use sched::{Poll, WasiSched};
-pub use string_array::StringArrayError;
+pub use string_array::{StringArray, StringArrayError};
 pub use table::Table;