identity API support through proper bindings

[shadeofblue]

• ensure ya-client contains definitions for the identity API (the /me endpoint of yagna's REST API)
• ensure there exists a ya-aioclient library version that contains bindings for the Identity API
• use the identity API where it's needed instead of calling the REST API directly from yapapi code

(currently the Identity API is only needed to support VPN creation in golem.create_network())

[filipgolem]

Another endpoint handled this way: /version/get.