Side drawer has been rewritten

• users now select an organization via a drop down.
• selecting an organization filters shown categories and tags.
• clicking a category or tag now selects only that category or tag by default.
• users can alt click to select multiple categories or tags.
• exclusive search is now the default.
• various frontend performance improvements.

- update download page with chrome extension
- fix welcome modal not opening on login
- fix category and tag dropdown not opening during onboarding tour
alert bar uses react context
- fix alert bar messing with onboarding tour popup location
-fix pressing enter on login screen when user has create account modal open is submitting the - login form, not create user form
minor updates to onboarding copy
- fix mobile side drawer onClose and onOpen not firing, breaking swipeable drawer
- intro.js highlighting fixed for SideDrawer and Modals

- upload bookmarks button on extension now properly redirects to web application.