[FEATURE] Meteor.methods resumability

As doc states ground:db doesn't support Meteor.methods() offline, but as ground:db is becoming more stable and more advanced, I think it could be time to add back features lost in the upgrade to V2 and THE feature lost is methods resumability. When one write in a grounded collection offline the data is sent as soon as the connection to the server is back (am I right ?), now ground:db just have to support method offline and all we be better than V1/post V1 definitively.
I think this feature is really important as it will improve the user experience A LOT, so our rich web application will be as good as natives apps ;)

The issue names no files, tests, or entry points. Start by reviewing GroundDB's existing offline write behavior and its integration with Meteor.methods; define how methods should resume after reconnection and what tests would demonstrate that behavior.

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