Implement fd_fdstat_set_flags for Windows.

This commit implements `fd_fdstat_set_flags` for Windows.

Additionally, it fixes a problem where `O_APPEND` was not working correctly
because `GENERIC_WRITE` was always being set; as a result, `FILE_WRITE_DATA`
could not be removed from the permission set to properly enable append-only
mode.

It also treats `O_TRUNC` with `O_APPEND` as an invalid argument error.  This is
because Windows cannot support these two flags together. To support `O_TRUNC`,
the `GENERIC_WRITE` bit must be set for the file access flags.  Setting this
bit will cause `FILE_WRITE_DATA` to be set, which will not properly treat the
file as append-only (it requires `FILE_APPEND_DATA` without `FILE_WRITE_DATA`).

crates/wasi-common/winx/src/file.rs

@@ -434,3 +434,20 @@ pub fn query_mode_information(handle: RawHandle) -> Result<FileModeInformation>
 
     Ok(FileModeInformation::from_bits_truncate(info.Mode))
 }
+
+pub fn reopen_file(handle: RawHandle, access_mode: AccessMode, flags: Flags) -> Result<RawHandle> {
+    let new_handle = unsafe {
+        winbase::ReOpenFile(
+            handle,
+            access_mode.bits(),
+            winnt::FILE_SHARE_DELETE | winnt::FILE_SHARE_READ | winnt::FILE_SHARE_WRITE,
+            flags.bits(),
+        )
+    };
+
+    if new_handle == winapi::um::handleapi::INVALID_HANDLE_VALUE {
+        return Err(winerror::WinError::last());
+    }
+
+    Ok(new_handle)
+}