wasi: fix threads option specification for wasmtime

In recent wasmtime, `-S` flags need to come after `run`.

Also add `-W threads=y` following the wasmtime test suite,

- fc3c868b13/tests/all/cli_tests.rs (L580-L581)

Also explicity enable the `cli` feature because this is used for CMake
try_run.

imagefiles/wasmtime-pwd-threads.sh

@@ -1,4 +1,4 @@
 #!/usr/bin/env bash
 
 # Mount the PWD and the /work mount dir to enable access in try_run commands
-exec ${WASMTIME_HOME}/bin/wasmtime -S threads=y run --dir=. --dir=$PWD --dir=/work/ "$@"
+exec ${WASMTIME_HOME}/bin/wasmtime run -W threads=y -S threads=y,cli=y --dir=. --dir=$PWD --dir=/work/ "$@"