feat(aggregate transform): add more aggregations to aggregate transform (#20836)

* feat(aggregate transform): add more aggregations to aggregate transform

Adds more functions to `aggregate` transform.

Closes: #3668

* Add changelog entry

* Add implementation for more aggregation functions

* Add test for min and max mode

* Implement Diff aggregation

* Add mean and stdev aggregations

* Update aggregate component docs

* Clean up mean calculation in metrics aggregation

Co-authored-by: Pavlos Rontidis <pavlos.rontidis@gmail.com>

* Remove `metric::` prefix in aggregate transform tests

* Emit errors when conflicting types are found during flush

* reduce code dulpication for MIN and MAX

* Clean up `record_count` in aggregate transform

Co-authored-by: Pavlos Rontidis <pavlos.rontidis@gmail.com>

* Remove unnecessary metric prefix in aggregate transform

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Co-authored-by: Pavlos Rontidis <pavlos.rontidis@gmail.com>