Proposal: `unnecessary_pattern` lint

[HosseinYousefi]

Consider this:

final foo = int.parse('1') == 1 ? '1' : null;
if (foo case final bar) {
  print(bar);
}

What we wanted to do is to check for foo's nullity, but actually we forgot to type ?. foo case final bar is unnecessary as it basically matches everything, it'd be good if we have a lint to warn us here.

[dart-github-bot]

Summary: Proposed lint unnecessary_pattern detects unnecessary case statements in pattern matching when the pattern matches all possible values, indicating a likely coding error. This helps catch unintended matches.