Add endpoints for user limits and usage

[m-murasovs]

These are currently missing, so on Console, we have to make regular API calls without the client. It would be better to use the client.

[mtrunkat]

Re-assigning this to Console as you added the endpoint and docs+client is a part of that work

[gippy]

We also need to add documentation for multifile select, just so that I do not forget.