Add a way to wait until changes are synchronized with fission

[matheus23]

Summary

I want to have a way to be notified until a .publish() call finally finishes synchronized the changes with the fission servers. I.e. to get notified when the "🪴 DNSLink updated: ..." message appears in the console after a publish call.

Problem

There is no API for that. There exists webnative.dataRoot.update, but it's not possible to use this API in conjunction with the FileSystem's publish: Publish will always call dataRoot.update without exposing the actual promise that does the work to the user.

Impact

In my UI I can't indicate to the user when a publish is in-progress. I have no way of figuring out when it's done.

Solution

I'm not sure. One way would be an option to turn off dataRoot updating in file systems.

[icidasset]

Implemented on next branch.