Add Proton Drive Support

[Xuanwo]

Proton Drive is part of proton's suite and used widely.

[zjregee]

It looks like Proton Drive hasn't provided a public API yet. And rclone offers beta version support for Proton Drive by reading the open-sourced client source code and observing the Proton Drive traffic in the browser, this may be a reference.

Here are some related links:

• https://www.reddit.com/r/ProtonDrive/comments/z1bofb/please_make_a_public_api_available_so_we_can_add/?rdt=59583
• https://rclone.org/protondrive/
• https://github.com/rclone/rclone/issues/6072

[Xuanwo]

Thank you so much for the research! Implementing support for Proton Drive is indeed a challenge.