Summary:
Like the welcome tour, a special URL hash triggers startDocTour which uses data from a table GristDocTour to construct the appropriate popups.
This is the basic version described in https://grist.quip.com/sN2RAHI2dchm/Document-tours
Test Plan:
Added a new nbrowser test which tests the data produced by makeDocTour. The general behaviour of the UI and popups has hardly changed so existing tests cover that well enough.
The new test uses a new fixture document which you can open to easily experience the tour.
Error cases where there's no valid document tour are not tested because that behaviour is likely to change significantly and this feature is still quite 'private'.
Reviewers: georgegevoian
Reviewed By: georgegevoian
Subscribers: jarek, dsagal
Differential Revision: https://phab.getgrist.com/D2938
