ROS2PoseControl: inconsistency in tag offset configuration

`ROS2PoseControlConfiguration` has two params:
- `m_useTagOffset`, and
- `m_startOffsetTag`

but the first one is used only to show/hide the second parameter in the GUI. 

In result, when `m_useTagOffset = false` and `m_startOffsetTag` has a proper tag string, then the offset tag will be used, even if `m_useTagOffset = false` might suggest the opposite.

