Filesystem: built-in file streaming feature

[szado]

Hello! 👋

Currently, the reactphp/filesystem component allows reading from and writing to files in chunks. Technically, this can be used for a simple file-streaming implementation, but performance is poor because getContents() and putContents() open and close the file on every call (at least with the EIO adapter). It would be great if this library offered native streaming functionality.

[WyriHaximus]

Yes, this is on the road map for either 0.2 or 0.3, depending on when my current open PR's get reviewed. This should be possible be all supported adapters. It should greatly improve performance but wanted to focus on the easy to use API first before adding streaming.