Support MySQL CHECK constraint enforcement

[minleejae]

Fixes #2526.

What

• Parse optional ENFORCED and NOT ENFORCED clauses after MySQL table-level CHECK constraints.
• Preserve the tri-state syntax on CheckConstraint through nullable Boolean getEnforced(): null when omitted, true for ENFORCED, and false for NOT ENFORCED.
• Deparse the explicit clause losslessly.
• Add a focused AST and parse/deparse regression test.

Server validation

The exact test statement was executed successfully on MySQL 8.4.11. information_schema.TABLE_CONSTRAINTS reported chk_positive as ENFORCED = YES and chk_cap as ENFORCED = NO.

MySQL grammar reference: https://dev.mysql.com/doc/refman/8.4/en/create-table.html

Testing

• ./gradlew clean test --tests net.sf.jsqlparser.statement.create.MySQLCreateTableConstraintTest --tests net.sf.jsqlparser.statement.create.CreateTableTest --tests net.sf.jsqlparser.statement.alter.AlterTest --no-daemon --no-build-cache -Dorg.gradle.vfs.watch=false
• ./gradlew spotlessApply check --no-daemon --no-build-cache -Dorg.gradle.vfs.watch=false

Both completed successfully.

AI assistance

OpenAI Codex was used to assemble and execute the parser/server comparison and prepare this change. The syntax was checked against the MySQL 8.4 documentation and an actual MySQL 8.4.11 server.