Implements read/write

[arcanis]

What's the problem this PR addresses?

Our FS layer doesn't implement read and write, which causes issues with some packages. One particular case is cp-file, which uses graceful-fs, which overrides our own createReadStream override with its own that simply returns new ReadStream, which has a regular open/read/close workflow.

How did you fix it?

• I've implemented read and write in FakeFS.
• In order to disambiguate whether a fd comes from the real filesystem or a zip one, the zip fds will have a special bit set (0x80000000). This bit would cause Node to reject the fd in other cases.

Which packages would need a new release (if any)?

berry-fslib / berry-cli / berry-pnp / berry-pnpify

Have you run yarn version [major|minor|patch] --deferred in those packages?

• Yes