Add `right` prop to NotebookCellItem (#17435)

* Remove not displayed NotebookCell's 'icon` prop

* Refactor NotebookCell to accent `right` prop

* Fix cypress getter

* Fix icons opacity

* Fix margins and paddings

* Pass initialState to getStore test helper

* Add basic tests for JoinStep

* Test automatic join fields assignment

* Add selectTable test helper

* Fix private property access

* Add join fields tests

* Test join is correctly applied to query

* Add more tests for join dimension pickers

* Test selecting joined table columns

* Disable failing JoinStep test (jest timeout)

* Extend timeout for JoinStep tests