DEBUG-2334 custom ActiveRecord model serialization

[p-datadog]

What does this PR do?

• Adds a custom serializer for ActiveRecord models
• Adds serializers for Time, Date and DateTime (needed for ActiveRecord timestamps)

Motivation:
AR models have many fields that are not interesting for DI, and serializing them would 1) consume a lot of resources 2) cause the serialized payload to exceed the limits of the backend 3) not serialize actual attributes due to depth limits (actual attributes are already 3 levels down from the AR model). The custom serializer currently only serializes the attributes, though additional fields can be added in the future such as the new_record? flag.

Change log entry

None

Additional Notes:

This PR is extracted from #4063 since the test failures there are difficult to troubleshoot.

How to test the change?
Unit tests are included

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-11-11 16:19:51

Comparing candidate commit 9d8830a in PR branch di-config-serialize with baseline commit 347bc45 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 29 metrics, 2 unstable metrics.