Fixes #11147

Motivation

• Add CaseParser class and its test cases
• Mysql doc: https://dev.mysql.com/doc/refman/8.0/en/flow-control-functions.html#operator_case
• CASE value WHEN compare_value THEN result [WHEN compare_value THEN result ...] [ELSE result] END
• CASE WHEN condition THEN result [WHEN condition THEN result ...] [ELSE result] END
  The first CASE syntax returns the result for the first value=compare_value comparison that is true. The second syntax returns the result for the first condition that is true. If no comparison or condition is true, the result after ELSE is returned, or NULL if there is no ELSE part.

Modifications

Verifying this change

(Please pick either of the following options)

• This change is a trivial rework/code cleanup without any test coverage.

• This change is already covered by existing tests, such as:
  (please describe tests)

• This change added tests and can be verified as follows:

  (example:)

  • Added integration tests for end-to-end deployment with large payloads (10MB)
  • Extended integration test for recovery after broker failure

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)
• If a feature is not applicable for documentation, explain why?
• If a feature is not documented yet in this PR, please create a follow-up issue for adding the documentation