Remove react-tether positioning library

[JanHamara]

Describe the feature you'd like

Based on RFC #217 - we have decided to replace react-tether positioning engine with react-popper

Describe alternatives you've considered

@floating-ui/react-dom - Discussion also on #217

What changes need to be done

• [x] Refactor Tooltip component to use react-popper
• [ ] Refactor Datepicker component to use react-popper (possibly reuse Popover component for Datepicker)
• [ ] Remove react-tether dependency from the project