draft of refactor to make custom confirm modal work for upload; need to further edit sb-file-uploader

Add support for custom confirm modal to sb-file-uploader

Show custom confirm modal when confirming project upload

got custom upload refactor of file upload working, and tested failure case

cleaned up debug code, make project file upload work

simplified logic around canceling file upload

removed old sb-file-uploader.jsx; fixed linter errors

reverted two components to use old strings, not shared

(can do that refactor another time)

removed unnecessary confirm container

removed stray comment

moved, updated sb file uploader tests, related project state tests

removed custom modal, to reduce scope of changes

sb file uploader test uses intl

simplify props of cloud-manager-hoc

Do not show unsupported browser modal for googlebot

Update scratch-l10n to the latest version 

Update library-item to handle 3.0 or 2.0 library formats

Update with render hotfix

[fixup] Implement sound downsampler to try to allow more sounds to be edited

Revert "Implement sound downsampler to try to allow more sounds to be edited"

Fix empty paint bug

Greenkeeper/scratch l10n 3.7.20200108141814

Closes #5354

Update scratch-blocks to the latest version 

Update scratch-paint to the latest version 

Update SVG Renderer

Update scratch-paint to the latest version 

Update scratch-render to the latest version