Fix isatty in WASI. (#3696)

WASI doesn't have an `isatty` ioctl or syscall, so wasi-libc's `isatty`
implementation uses the file descriptor type and rights to determine if
the file descriptor is likely to be a tty. The real fix here will be to
add an `isatty` call to WASI. But for now, have Wasmtime set the
filetype and rights for file descriptors so that wasi-libc's `isatty`
works as expected.

crates/wasi-common/cap-std-sync/Cargo.toml

@@ -30,6 +30,7 @@ rustix = "0.31.0"
 [target.'cfg(windows)'.dependencies]
 winapi = "0.3"
 lazy_static = "1.4"
+atty = "0.2.14"
 
 [dev-dependencies]
 tempfile = "3.1.0"