Extend limit&offset statements

[Lagovas]

Extended parser with postgresql specific statements syntax and refactored rendering from the AST to the string in same format as it was parsed.
But wasn't added support of cursor specific syntax for PostgreSQL with FETCH + limit&offset. It is much more complicated and should be implemented together with cursor's support.
PostgreSQL's format - https://www.postgresql.org/docs/current/sql-select.html#SQL-LIMIT
MySQL's format - https://dev.mysql.com/doc/refman/8.0/en/select.html

Checklist

• Change is covered by automated tests
• 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)
• Example projects and code samples are up-to-date (in case of API changes)

[Zhaars]

As I understand, currently, all of these syntax constructions are supported by both MySQLDialect and PostgreSQLDialect. Does it make sense to throw some error in case of a non-specific DB format?

In this test, we consider select * from dual limit all with MySQLDialect as valid SQL, but it's not.

[Lagovas]

agree, added errors and tests for these cases. additionally I found how we can configure verbosity of loggers in parser and tokenizer. I just decreased verbosity of tokenizer for acra in non-debug mode to avoid logging sensitive parts of SQL query which we cannot control. But now I keep in mind this options that may help in debugging and extending parser.

[Zhaars]

Lgtm