Add action 'user password set' for identiy v3

This new action will allow a user to change their own password by
either providing the new password as an argument (--password) or by
being prompted to enter the new password.
In both cases user will be prompted to enter their current password
as required by the v3 API.

Closes-Bug: #1337245
Change-Id: I5e1e0fd2b46a4502318da57f7cce2b236fb2d93d
Merge "Add action 'user password set' for identiy v3"