restructure cap-std impls into their own crate

crates/wasi-c2/src/file.rs

@@ -166,46 +166,3 @@ pub struct FdStat {
     pub caps: FileCaps,
     pub flags: FdFlags,
 }
-
-impl WasiFile for cap_std::fs::File {
-    fn as_any(&self) -> &dyn Any {
-        self
-    }
-    fn datasync(&self) -> Result<(), Error> {
-        self.sync_data()?;
-        Ok(())
-    }
-    fn sync(&self) -> Result<(), Error> {
-        self.sync_all()?;
-        Ok(())
-    }
-    fn get_filetype(&self) -> Result<FileType, Error> {
-        let meta = self.metadata()?;
-        Ok(FileType::from(&meta.file_type()))
-    }
-    fn get_fdflags(&self) -> Result<FdFlags, Error> {
-        // XXX get_fdflags is not implemented but lets lie rather than panic:
-        Ok(FdFlags::empty())
-    }
-    fn set_fdflags(&self, _fdflags: FdFlags) -> Result<(), Error> {
-        todo!("set_fdflags is not implemented")
-    }
-    fn get_filestat(&self) -> Result<Filestat, Error> {
-        let meta = self.metadata()?;
-        use cap_fs_ext::MetadataExt;
-        Ok(Filestat {
-            device_id: meta.dev(),
-            inode: meta.ino(),
-            filetype: FileType::from(&meta.file_type()),
-            nlink: meta.nlink(),
-            size: meta.len(),
-            atim: meta.accessed().map(|t| Some(t.into_std())).unwrap_or(None),
-            mtim: meta.modified().map(|t| Some(t.into_std())).unwrap_or(None),
-            ctim: meta.created().map(|t| Some(t.into_std())).unwrap_or(None),
-        })
-    }
-    fn set_filestat_size(&self, size: u64) -> Result<(), Error> {
-        self.set_len(size)?;
-        Ok(())
-    }
-}