Storage node should not provide NeoFS Object API service when it is
under maintenance.
Declare `Common` service that unifies behavior of all object operations.
The implementation pre-checks if node is under maintenance and returns
`apistatus.NodeUnderMaintenance` if so. Use `Common` service as a first
logical processor in object service pipeline.
Signed-off-by: Leonard Lyubich <ctulhurider@gmail.com>
