Model MySQL CREATE EVENT and ALTER EVENT

[minleejae]

Summary

• parse MySQL CREATE EVENT and ALTER EVENT as dedicated statements
• expose one-time and recurring schedules, bounds, completion policy, status, comments, rename targets, and bodies as structured AST values
• route event bodies through visitors so contained table references and validation remain usable

Validation

• ./gradlew spotlessApply test spotlessCheck checkstyleMain checkstyleTest
• executed create, reschedule, body replacement, disable, and rename flows against MySQL 8.4

[manticore-projects]

Please resolve conflicts.

[minleejae]

@manticore-projects The merge conflicts have been resolved, and the branch has been rebased onto the latest master. This PR is ready for review again. Thank you.

[manticore-projects]

Sorry, it keeps colliding since all those affect the Visitors and Adaptors. Fix one first, I merge prompt. Then the remaining one.