feat: Add synology file station support

[Xuanwo]

It seems interesting to add synology file station support in OpenDAL so users with synology can use applications that powered by OpenDAL to access data directly.

API Docs

Problems

Use cases

Will users want to use this service? Maybe it's easier to mount to local and use POSIX fs directly?

Integration tests

But synology file station is part of synology's DSM which is limited to install on synology's hardware.

I'm not sure if we can use https://github.com/kroese/virtual-dsm to perform integration tests in our CI.

[prabirshrestha]

Here are some info I have which may be helpful for future.

Currently I mount local in docker and use POSIX directly. The only issues I have seen with this is other apps in synology such as photos may not index it so you need to manually run it. Synology does support SMB and webdav which needs to be enabled separately so you can always connect to those instead. SMB and webdav bypasses 2fa and doesn't require the code while their filestation api requires 2fa code if it supports.

Folks have written workarounds to index.

• https://github.com/racklin/simple-synoindex-server
• https://github.com/bonidier/synodlna-index
• https://github.com/carljm/synology-mediamon
• https://gist.github.com/tomitrescak/03959524c31e3a889c4d43f53c2390ac

If you directly mount posix fs, you can access their thumbnails. If you have a file /volume1/photos/1.jpg you can get it's thumbnail from /volume1/photos/@eaDir/1.jpg/SYNOPHOTO_THUMB_XL.jpg.

When using POSIX if the dir has lot of files it can be slow while using their api directly means they store it in postgres db so it can be faster to list.