Add more file-like methods to the python bindings

[mobiusklein]

This adds the following methods to the File type in the Python bindings:

• flush
• readable
• writable
• seekable
• closed
• readinto

For AsyncFile, the following were added:

• readable
• writable
• seekable
• closed

Manually testing was done locally, but I couldn't get the unit tests to run due to environment dependency issues. Hopefully CI will trigger here.

[mobiusklein]

This partially addresses #4384. It assumes that all readable services support seeking, which may not be valid, but it mirrors the implementation seek.

[messense]

It assumes that all readable services support seeking

Can you use https://docs.rs/opendal/latest/opendal/struct.Capability.html#structfield.read_can_seek?

[Xuanwo]

This is an ongoing RFC related to this: #4382

[mobiusklein]

I've added the capability check to the Python bindings, but is there anything specific I should do w.r.t. the RFC? Or is it just a blocker for this PR?

[Xuanwo]

Or is it just a blocker for this PR?

After this RFC been implemented (which is already going on), we might need to change the way of implement File in python.

[Xuanwo]

Hi, @mobiusklein, sorry for the long waiting. I feel like this PR is good to go. Would you like to fix the CI issues so we can get it merged?

[mobiusklein]

Is it correct to say that seek operations are now supported universally since the behavior is no longer described by the Capability type? I don't see any documentation about it except for an outdated note in https://opendal.apache.org/docs/rust/opendal/struct.Capability.html#naming-style.

[Xuanwo]

Is it correct to say that seek operations are now supported universally since the behavior is no longer described by the Capability type?

Yes!

[mobiusklein]

Thank you. I've refactored the bindings to reflect that. The Capability struct the File types carry around now probably is no longer relevant but I left it there for the future. I'll have to re-digest what the capabilities mean but on my first pass I don't see a way they'd intrude into the Python API.

[mobiusklein]

Things appear to be all set now. Thank you.

[Xuanwo]

Thanks a lot!