fix: reuse structured constraints for MySQL inline CHECK

[minleejae]

MySQL column CHECK clauses with ENFORCED or NOT ENFORCED are not handled consistently with table constraints. Route column checks through the existing CheckConstraintSpec production and CheckConstraint AST.

CREATE TABLE and ALTER ADD/MODIFY/CHANGE already share column option parsing; all now retain the constraint name, expression, and enforcement flag, including custom expression deparsing.

Validation:

• Full Gradle check passed (Java 17), including grammar ambiguity, unit tests, coverage, formatting, Checkstyle, PMD, and SpotBugs.
• MySQL 8.4.11 accepted negative values for NOT ENFORCED checks in all four CREATE/ALTER paths; original, toString, and deparser SQL behaved identically.
• Added AST, mutation, and parse/deparse regression coverage.

Syntax reference: official documentation.

Additional version-boundary validation: the original, toString, and deparser SQL was executed on isolated MySQL 9.7.2 and 26.7.0 servers, including the focused behavioral cases. Also tested PostgreSQL 18.6 inline CHECK NOT ENFORCED with and without NO INHERIT, and added regressions. Reviewed the MySQL 9.7 and MySQL 26.7 grammar. Runtime version numbers above identify the tested binaries; this does not claim support for every statement in those DBMS versions.

[manticore-projects]

Thank you!