Open project from file explorer

[charlielee]

The .baproject file extension should be registered with the shell to enable opening Boats Animator projects straight from the file explorer.

It should also be possible to drag a file onto the Boats Animator task bar/dock icon to open it.

Should be able to handle if a project file is opened and Boats Animator is already open.

https://www.electron.build/configuration/configuration.html#overridable-per-platform-options