Edge can't parse CSS hsla() values without an alpha component.

Override the z-index for the blocks drag layer. At 1000, it will be over everything in the gui other than the navbar itself (monitors on the stage, tutorials, alerts, dropdown menus, etc.)

fixes https://github.com/LLK/scratch-www/issues/2587
and https://github.com/LLK/scratch-gui/issues/4428

changed menu-bar z-index to one more than monitors so drop down menus cover monitors when opened.

See #4382 for more info about why, and what we need to follow up on it

Fixes useability issue where the drop area was too small, and you couldn't see it.

made alert messages translation-ready
updated project saver hoc
default alerts to COLOR_ORANGE

got tests working

made neutral button color

Put stage, monitors, add buttons, tooltips, menubar under the block drag layer. Make sure the Extension button is above the toolbox.

* 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

padding and margin changes to make www project page layout work without hacks; hack to position monitors correctly

This bled into normalizing z-indices for the action menus in the z-index.css. The tooltip id was not unique between action menus for ‘suprise’ and ‘paint’, so `mainTooltipId` was used as a prefix to make them unique.

In addtion to changing the UI color for “mini cards” from motion blue to extensions aqua, this commit also updates the color variable previously known as ‘$pen-primary’ to ‘$extensions-primary’.

- Auditing color CSS and componet CSS to make consistent.
- Made a first pass of changes to increase contrast to elements that previously were problematic

Initial SB2 Import UI (button in preview modal + import modal that can load projects via url). Preliminary validation on url, still needs error handling.

- implements welcome to the preview modal, and unsupported browser modal.
- will need assets updated in Jan.