Deprecate `tokenize` option

[G1gg1L3s]

This PR deprecates tokenize from encryptor config. It is still present, but it's role is taken by token_type - if it's not empty, the tokenization is enabled.

Also, forbids the tokenize: false and token_type: <something> pair.

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 - https://github.com/cossacklabs/product-docs/pull/244
• [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)~