Fix failing test with searchable tokenization

[Zhaars]

Fix the failing test with searchable tokenization. Updated pgsql Coder with additional logic on Encode method to check if the data need to be encoded to hex or returned as is.

Checklist

• [x] Change is covered by automated tests
• [x] The coding guidelines are followed
• [ ] Public API has proper documentation in the Acra documentation site or has PR on documentation repository with new changes
• [ ] CHANGELOG.md is updated (in case of notable or breaking changes)
• [ ] CHANGELOG_DEV.md is updated
• [ ] Benchmark results are attached (if applicable)
• are up-to-date (in case of API changes)