feat(user/status): Add support for clear_status_after / clear_status_at.

feat(user/status): Add support for clear_status_after / clear_status_at.

SetUserStatus

Adds the ability to automatically clear a user's status after a specified time period.

• The ClearStatusAfterValue type has been added with appropriate constants for all supported durations.
• The ClearStatusAfter field has been added to the UserStatusOptions struct.
• A unit test for SetUserStatus has been added.

CurrentUserStatus / GetUserStatus

The time at which a status will be cleared is now exposed via the Go structure.

• The ClearStatusAt field has been added to the UserStatus struct.
• The unit test has been updated to cover parsing of the ClearStatusAt field.