Multiple open `Handle`s for the same file don't share metadata

Multiple open `Handle`s for the same file don't share metadata, meaning the inode can get out of sync. Repro: ```ts import * as fs from '@zenfs/core/promises'; // more readable await fs.writeFile('example.txt', 'Hello World'); const a = fs.open('example.txt', 'r+'); const b = fs.open('example.txt', 'r+'); await a.truncate(5); // Contents are now "Hello" const { size } = await b.stat(); assert.equal(size, 5); // fails because `b` doesn't have the updated metadata from `a` ``` The fix for this is to have `Handle`s share their `inode` via a semi-global cache, which can be keyed using the FS' `uuid` and the file's `ino`.