Add "before:" and "after:" parameters to the scan verb #233

Is your feature request related to a problem? Please describe.

For clients which do not need or want a full "sync" implementation (i.e. persistent local cache of the data), there is currently no way to scan for keys which have been updated since some timestamp.

Describe the solution you'd like

Allow clients to issue queries like "get me all keys matching some regex which were last updated (incl created) after after and/or before before where both before and after are millisecondsSinceEpoch values.

Proposal:

• add optional :before:\d+ and :after:\d+ to the scan verb syntax in at_commons
• modify the ScanVerbBuilder in at_commons and adding the new parameters to the AtLookup interface's scan function
• modify atServer as required starting with ScanVerbHandler

Describe alternatives you've considered

No response

Additional context

No response