WIP: Failing integration test for new change password functionality.

- Pull more helper methods out into TestClient.
WIP: New ChangePassword endpoint on Login Server

- Calls UAA with PUT /Users/{userId}/password
- TODO: Authenticate with user credentials to find userId
New change password form page.
Change link on account settings page to point to new change password flow.
WIP: Rollback multiple RestTemplates in ChangePasswordService.
UaaChangePasswordService uses the updated uaa password_change endpoint

[#66711370]
Change Password page validates password confirmation, handles errors

[#66711370]
Merge branch 'feature/change_password' into develop