This commit updates _all_ WASI test programs to use the latest
version of the `wasi` crate (`v0.9.0`). While at it, it also
unifies asserting error conditions across all test programs.
* Move `wasi` to `wasi_old` in wasi-tests
Leave space for the new `wasi` crate but allow us to incrementally
update tests.
* Update the big_random_buf test
* Update clock_time_get test
* Update close_preopen test
* Review comments
* Update to latest Wasmtime API
* Reorganize wasi-misc-tests.
Move wasi-misc-tests out of wasi-common, to break a dependency cycle;
previously, wasmtime-* depended on wasi-common, but wasi-common
dev-dependended on wasmtime-*.
Now, wasi-common no longer dev-depends on wasmtime-*; instead, the
tests are in their own crate which depends on wasi-common and on
wasmtime-*.
Also, rename wasi-misc-tests to wasi-tests for simplicity.
This also removes the "wasm_tests" feature; it's replaced by the
"test-programs" feature.
* Update the CI script to use the new feature name.
* Update the CI script to use the new feature name in one more place.
* Change a `write!` to a `writeln!`.
