Implement Hashicorp Consul encryptor config loading

[Zhaars]

Implementation of loading encryptor_config from Hashicorp Consul. Approach with global registry map and build flag was used to achieve flexibility.

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)
• [x] CHANGELOG_DEV.md is updated
• [ ] Benchmark results are attached (if applicable)
• are up-to-date (in case of API changes)