[analyzer] No error if a local variable named augmented is declared inside of augmenting function

[sgrekhov]

The following co19 tests fail because of this issue

co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A01_t12
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A01_t13
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A01_t14
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A01_t15
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A01_t16
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A01_t17
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A02_t11
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A02_t12
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A02_t13
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A02_t14
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A02_t15
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A02_t16
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A03_t15
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A03_t16
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A03_t17
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A03_t18
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A03_t19
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A03_t20
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A04_t04
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A04_t05
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A04_t06
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A04_t07
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A04_t08
co19/LanguageFeatures/Augmentation-libraries/augmented_expression_A04_t09

This happens when augmented variable is declared by the pattern. According to the spec inside of augmenting function augmented became a keyword referencing the original function. So, declare a variable named augmented is a compile-time error

Example

augment String get topLevelGetter {
  var (augmented) = (42);
//     ^^^^^^^^^
// [analyzer] unspecified
// [cfe] unspecified
  return "Augmented";
}