Allow joins on multiple fields in the notebook editor (#17633)

* Separate Join unit tests with newlines

* Refactor Join's unit tests

* Add join type getters (by conditions count)

* Add getter and setter for join conditions by index

* Remove old comment

* Extract method converting dimensions

* Update setParentDimension

* Update setJoinDimension

* Update joinDimensions method

* Update joinDimensions method

* Update join alias setter

* Update default condition setter

* Update isValid method

* Add getConditions method

* Add addEmptyDimensionsPair method

* Render multiple join conditions

* Fix JoinStep align-items

* Fix join dimension methods usage

* Fix join dimensions alignment

* Temporary disable auto opening pickers

* Test adding a new dimensions pair

* Fix "add" join icon visibility

* Add "on" label between join conditions

* Remove redundant `else`

* Add `removeCondition` method for `Join`

* Fix JoinDimensionPicker's prop types

* Allow removing empty dimension pairs

* Add space between join dimensions

* Simplify JoinStep tests setup

* Automatically open dimension pickers

* Test JoinStep updates `Join` instance correctly

* Display dimensions source name

* Allow overwriting NotebookCell's padding

* Fix JoinStep layout

* Allow to clear a selected dimension

* Disable "no-unused-vars" for Join file

* Fix parentDimension usage

* Fix StructuredQuery's `Join` usage

* Update notebook visual test

* Fix E2E test

* Fix JoinStep look when no dimensions selected

* Extract JoinDimensionsRightControl component

* Extract JoinDimensionCellItem component

* Increase JoinStep's tests timeout

* Extract `_getExplicitJoinsSet` from StucturedQuery

* Fix unused variables in Join class

* Add a comment about setTimeout

* Fix join condition label

* Fix dimensions picker opens when dimension is set

* Make table icon container clickable

* Hide fields picker tooltip on picker open

* Fix Preview button overflowing JoinStep

* Fix table picker click area