Implement setting worker state

Implement setting worker state

In order to perform maintenance, Worker should be in a proper state.
Administrator should set state to MAINTENANCE before taking action
and set it back to IDLE so it will return to the pool.

Change-Id: I44e2c64645e3643c16e8484c746ae4a233a6d232
Signed-off-by: Aleksander Mistewicz <a.mistewicz@samsung.com>
Reviewed-on: https://mcdsrvbld02.digital.local/review/49059
Reviewed-by: Maciej Wereski <m.wereski@partner.samsung.com>
Tested-by: Maciej Wereski <m.wereski@partner.samsung.com>