Rewrited convert to Visitor Interface from ANTLR4 + fixed some types casts & error texts

[1NepuNep1]

Related to (#8)

[Copilot]

Pull Request Overview

This pull request refactors the YDB parser to use ANTLR4's Visitor interface pattern instead of a custom convert method, while also adding several utility functions for collecting different types of operators and improving type safety.

• Replaced custom convert() method with ANTLR4's Accept() visitor pattern
• Added type safety checks and error handling for visitor pattern conversions
• Introduced utility functions for collecting comparison, bitwise, addition, and equality operators

Reviewed Changes

Copilot reviewed 3 out of 5 changed files in this pull request and generated 1 comment.

File	Description
internal/engine/ydb/utils.go	Refactored extractRoleSpec to use visitor pattern and added operator collection utility functions
internal/engine/ydb/parse.go	Updated statement parsing to use visitor pattern with proper type checking
go.mod	Updated yql-parsers dependency version

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