Add response on fail for mysql

[G1gg1L3s]

Mysql doesn't respond to the different options of the response_on_fail (default_value, error and ciphertext) field. This PR changes that and bring support as in https://github.com/cossacklabs/acra/pull/521.

Checklist

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