[exporter/clickhouseexporter] Support JSON type for logs and traces

[SpencerTorres]

Description

Depends on refactoring from #40536

Adds JSON support to the exporter.

Summary:

• Added feature gate (clickhouse.json, alpha stability) for enabling the JSON type pipeline. The Map based pipeline is still functional and is the default. (How to use feature gates)
• The JSON type replaces all Map columns with the new JSON type.
• JSON is sent to the server as a string.
• Due to how the server stores JSON paths, OTel standard paths such as a.b.c are returned as objects a { b { c } } by the server. This can be changed via server setting in the future to return all data as flattened paths a.b.c.

Let me know if you have any questions, suggestions, etc.

Thanks!

Testing

• Added unit tests for related helper functions
• Added integration tests for JSON logs/traces

Documentation

• Updated README, changelog

[SpencerTorres]

This PR includes a driver update that fixes the HTTP pipelines, if we don't get this merged before the next release I can submit a separate PR to update the module.

clickhouse-go v2.37.1 includes the fix, main is currently on v2.37.0

Without the fix, HTTP pipelines risk starving connections and inconsistent HTTP/400 errors.

Resolved in #40766