* added account navigation menu, copied and adapted from www

* fixed css

* support for login menu, registration menu from www

* Dropdown replaced with MenuBarMenu, override www css in menus

* render and style login dropdown via function from www

* moved menu styling from menu itself to menu bar

* refactoring menu components and containers

* refactor and restyle account nav menu

* cleaned up cruft and css per rschamp's review of PR 3070

styling for title field; correct input target in tests; make download filename safer with default, max length; in playground index, correctly pass props through to gui container

Unfortunately I couldn't do the same with loading projects, since the presence of the component (necessitating the menu to be open) allows the actual upload from file to work, since it needs the FileInput component to be present, so it can emit a change event.  We should revisit

Overlay a transparent `select` over the language icon. When a user clicks there the options pops up. There’s no styling of the options, other than font and font size.

This reverts commit 1c20d6db, reversing
changes made to 2f1cce93.

Note: the coming soon tooltip positions are calculated by react-tooltip, and they do not handle RTL.

added a line to manu-bar css so as to prevent brokenness in nav bar in Japanese and Chinese languages.

HT @paulkaplan

The onMouseUp handler for the menu rerenders the language menu before the select onChange function runs on Firefox. So it resets the language value back to the previous value and the locale doesn’t update. If the languageMenu isopen don’t fire the openlanguageMenu action.

* refactor LanguageSelector to reuse MenuBarMenu
* localize aria-labels on MenuBar

Allows the language selection menu to be active if `?enable=language` is in the URL, otherwise shows a ‘coming soon’ tooltip. This can also land on a branch if we don’t want that available on preview.

- language menu opens if the globe is clicked
- language menu closes if mouse is clicked anywhere outside the language selector
- language list is imported from scratch-l10n
- current locale is updated if another language is selected (i.e. the current language selected changes)

Not in this PR:
- styling of language selector
- actually changing the messages!

It was 435KB. Now it's 5KB. I used SVGOMG: https://jakearchibald.github.io/svgomg/