Resolves https://github.com/LLK/scratch-gui/issues/1713

Resolves #1644

Revert "Changes to hash should happen through project loader hoc. Changes to the current project id and current project data should happen in a reducer since they are part of global state. That way, the load button can affect the global project data as well."

This reverts commit e4fe143b.

FWIW the AP style guide recommends "emojis", although many dictionaries
also recognize "emoji" as the plural because that is the plural in the
original Japanese.

Changes to hash should happen through project loader hoc. Changes to the current project id and current project data should happen in a reducer since they are part of global state. That way, the load button can affect the global project data as well.

Remove .sb from file browser filter since we can't support them yet. Remove .zip from the same. Save project as .sb3 (and untitled-project).

scratch-audio depends on sound property being called md5 even though it refers to md5+file ext,
so this property cannot be renamed just yet.

This reverts commit dee7195f.

Added:
- Opera (including Opera Mini)
- Silk

Not Added:
- Vivialdi - appears to be ‘Chrome’ in `platform.name`

Load button file input should only accept specific file extensions. Update load button to use new revamped loadProject function from VM. Loading a project via load button should clear the url hash (without triggering a reload or the project-loader-hoc).

Removing JSZip dependency. VM will unpack the zip (for now, until this functionality gets moved to scratch-storage).