Fix wrong question_mark suggestion when match arm body is a destructuring assignment

[charlieHsiuC]

• Added && sugg.starts_with('{') to the block-insertion branch. When the snippet doesn't start with { (i.e., destructuring assignment), it falls through to the else branch which correctly wraps the suggestion in an explicit block.
• Added a new test case issue_destructuring_assignment in tests/ui/question_mark.rs to verify that the lint provides correct suggestion for match expressions with destructuring assignments that can be replaced by the ? operator.

fixes #16862

changelog: [question_mark]: Fix wrong suggestion when match arm body is a destructuring assignment