* Add mic indicator

* Fix mic indicator position and margin

* Don’t always show indicator, don’t sneaky-enable extension

* Position mic indicator in RTL

* Actually, don’t move indicator in RTL

* Update event name for MIC_LISTENING

* Move mic indicator state into redux

* Move stageSizeToTransform into screen-utils

* Position mic indicator and question at bottom of stage

* Fix pointer events

* JSDOC for stageSizeToTransform

* Pass micIndicator into StageComponent via …props

Moving click handling to alert component from container in order to handle index correctly.  Removed AlertsComponent and added new AlertComponent.

* 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

For use from `scratch-desktop` and maybe other places...

I left the ability to ignore languages in place so that we can continue to have languages that are available, but not in the menu for everyone.

Follow up on #2464, fix the hacky accessors into the vm and renderer internals.

* convert all tags to have a `tag` field corresponding to the query parameter, and `intlLabel` field that defines the title message for `FormattedMessage`
* define all the tag messages in a shared file so they can be included in multiple places.
* convert the `TagButton` to use `tag` for the `onclick` handler value, and localize `intlLabel` for the title.

In the library I’ve continued to use `tag.toLowercase()` even though all the tags are currently defined as lowercase. It’s safer, but currently not strictly needed.

Questions:
* should the message strings include the number? Or should that get added to the name when the name is defined
* added a new ‘shared-messages’ to handle the definition of backdrop, costume, etc which are used in multiple places, they’re all related to defaults, so should it all be in `lib/default-project`