Support unique metrics on additional properties

Problem

When choosing a unique criteria for a metric we only support the properties from standard context user/namespace/project. While those are the most likely ones to be used for unique values there might be cases where metrics based on unique additional properties are necessary

Desired Outcome

unique for metrics supports additional properties (e.g. label etc.)

Potential Solution

1. In InternalEvents, add handling for the new property_name values
2. Verify this for RedisHLLMetric, TotalCountMetric and AggregatedMetric classes. AggregatedMetric would need an addition into its mapping. Asides from that, I think these classes should work out of the box.
3. Modify the generator cli to make it possible to create such metrics.

How to verify

TBD

Further actions needed

TBD