FEAT save state to and load state from cloud storage

[hgkamath]

Is your feature request related to a problem? Please describe.
No, only that one should not to be restricted to using the app on only one machine

Describe the solution you'd like

• save state to and load state from cloud storage
• to be able to access todo-lists on any device.

My understanding so far, is that condution saves its state in browser cache/storage.
There are many cloud storage providers such as google-drive, dropbox, onedrive, box etc.
There are javascript cloud storage adapters that perhaps interface with many storage providers.
saving state via ical could be another way
saving state via webdav could be another way

One may then also need the following. These could be filed as follow on bugs if and when condution supports cloud storage.

• to ensure some synchronization mechanism so that data not clobbered by simultaneous access.
• to ensure some encryption/decryption so that data is safe on 3rd party provider

Additional context
na