Add optional actix web feature

[nayyara-airlangga]

Actix Web is an established and vastly used web framework in the Rust community. In my opinion, adding support for such a major web framework early on would be a great way to add more value to the project.

The feature may include the following implementations:

• Middlewares for bearer token authorization (both for access and refresh tokens)
• Login, logout, and get self (sso user) web handlers.
• Handler to generate new access and refresh tokens

I'll be implementing this feature myself if possible in the next few days. If anyone would like to implement this optional feature, please comment on this issue. Thank you.