VFS Capability detection, other extensions

[andersevenrud]

VFS could benefit from capability detection so that clients is aware of what a filesystem source is capable of.

This would allow for adding extensions on the client that are context aware, like pagination and archives.

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Split out from discussions in:

• Improve serialization of VFS URL query parameters osjs-client#165
• Improve unserialization of VFS URL query parameters osjs-server#56

Work done on this:

• Fix unused options in readdir system VFS adapter osjs-client#164
• Support serialization of url query parameters osjs-client#182
• Add VFS capabilities method osjs-client#186
• Add VFS capability caching osjs-client#188
• Add VFS context aware sorting osjs-client#189
• VFS Archive support osjs-client#190
• Support unserialization of url query parameters osjs-server#63
• Add VFS capabilities method osjs-server#65
• Add totalSize and totalCount values to VFS stats osjs-server#66
• VFS Archive support osjs-server#67
• Adding pagination capability osjs-filemanager-application#37

Pending:

• VFS Archive support osjs-server#64
• VFS Archive support osjs-client#184
• Unzip option for zip files osjs-filemanager-application#39

Relevant:

• Support VFS methods with no argument #788
• Add option interface for VFS readdir osjs-client#163
• Gradual fetching of data by scrolling down in File Manger Application osjs-client#166

[andersevenrud]

As discussed, @mahsashadi will do some work related to this in the following stages:

1. URL serialization (done)
2. Client option filtering
3. Capability detection (done)
4. Other improvements

Massive thanks!

[andersevenrud]

Also, @ajmeese7 wanted to have a look at archive extensions.

Thanks a bunch!

[mahsashadi]

I continue with capability detection of VFS:
os-js/osjs-client#186
os-js/osjs-server#65

These changes are considered added method has some argument. If you still have the idea of capability caching, maybe we should create another PR that changes the api to support methods without arguments.
I remember I worked on this issue but did not come up with solution.

[andersevenrud]

@mahsashadi Yeah, let's tackle the caching in a separate PR. It needs further discussion. I have some ideas about this already, but let's take it when the time is right.