Update WASI tests to use wasi crate v0.9.0 (#743)

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.

crates/test-programs/wasi-tests/Cargo.toml

@@ -9,7 +9,6 @@ publish = false
 [dependencies]
 libc = "0.2.65"
 wasi = "0.9.0"
-wasi-old = { version = "0.7.0", package = "wasi" }
 more-asserts = "0.2.1"
 
 # This crate is built with the wasm32-wasi target, so it's separate