fix: add fail assertion as a valid method to missing_test_assertion rule

lib/src/analyzers/lint_analyzer/rules/rules_list/missing_test_assertion/visitor.dart

@@ -74,6 +74,7 @@ class _MethodAssertionVisitor extends RecursiveAstVisitor<void> {
     'expectAsyncUntil5',
     'expectAsyncUntil6',
     'expectLater',
+    'fail',
   };
 
   _MethodAssertionVisitor(Iterable<String> includeAssertions) {

test/src/analyzers/lint_analyzer/rules/rules_list/missing_test_assertion/examples/correct_example.dart

@@ -74,5 +74,9 @@ void main() {
     expectAsyncUntil6((p0, p1, p2, p3, p4, p5) {}, () => true);
   });
 
+  test('with fail', () {
+    fail('some failure reason');
+  });
+
   test(null, () => expect(1, 1));
 }

website/docs/rules/common/missing-test-assertion.mdx

@@ -5,7 +5,7 @@ import RuleDetails from '@site/src/components/RuleDetails';
 Warns that there is no assertion in the test.
 
 Use `include-assertions` configuration, if you want to include specific assertions.
-Defaults to Dart default assertions including expect, expectLater and all expectAsync variants.
+Defaults to Dart default assertions including expect, expectLater, all expectAsync variants and fail.
 
 Use `include-methods` configuration, if you want the linter to check particular test methods for missing assertions.
 Defaults to `test` and `testWidgets` methods.