Feature: Persist effect of "SET ROLE" queries.

[chernser]

Summary

Implement setting role per java client. The main goal is to persist set of roles between different HTTP calls because there is no persistent session for a user in that case.

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG
• For significant changes, documentation in https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials

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[mzitnik]

LGTM

[mzitnik]

delete blank line

[slvrtrn]

@chernser, let's retest with the head version of the ClickHouse docker image and merge it.

[sonarqubecloud]

Quality Gate failed

Failed conditions
65.6% Coverage on New Code (required ≥ 80%)

See analysis details on SonarCloud