bug: defaulted `friend` operators get incorrectly parsed as declarations

[xhrnca00]

Did you check existing issues?

• I have read all the tree-sitter docs if it relates to using the parser
• I have searched the existing issues of tree-sitter-cpp

Tree-Sitter CLI Version, if relevant (output of tree-sitter --version)

No response

Describe the bug

In C++20, operator== and operator<=> can get marked as default. These operators do not have to be methods and can be friends instead. This does not get parsed correctly.

Steps To Reproduce/Bad Parse Tree

Example (adapted from Default comparisons (cppreference))

struct X
{
    bool operator==(const X&) const = default;
    friend bool operator==(X, X) = default;
};

(Bad) tree:

(translation_unit ; [0, 0] - [5, 0] cpp
  (struct_specifier ; [0, 0] - [4, 1] cpp
    name: (type_identifier) ; [0, 7] - [0, 8] cpp
    body: (field_declaration_list ; [1, 0] - [4, 1] cpp
      (function_definition ; [2, 4] - [2, 46] cpp
        type: (primitive_type) ; [2, 4] - [2, 8] cpp
        declarator: (function_declarator ; [2, 9] - [2, 35] cpp
          declarator: (operator_name) ; [2, 9] - [2, 19] cpp
          parameters: (parameter_list ; [2, 19] - [2, 29] cpp
            (parameter_declaration ; [2, 20] - [2, 28] cpp
              (type_qualifier) ; [2, 20] - [2, 25] cpp
              type: (type_identifier) ; [2, 26] - [2, 27] cpp
              declarator: (abstract_reference_declarator))) ; [2, 27] - [2, 28] cpp
          (type_qualifier)) ; [2, 30] - [2, 35] cpp
        (default_method_clause)) ; [2, 36] - [2, 46] cpp
      (friend_declaration ; [3, 4] - [3, 43] cpp
        (declaration ; [3, 11] - [3, 43] cpp
          type: (primitive_type) ; [3, 11] - [3, 15] cpp
          declarator: (init_declarator ; [3, 16] - [3, 42] cpp
            declarator: (function_declarator ; [3, 16] - [3, 32] cpp
              declarator: (operator_name) ; [3, 16] - [3, 26] cpp
              parameters: (parameter_list ; [3, 26] - [3, 32] cpp
                (parameter_declaration ; [3, 27] - [3, 28] cpp
                  type: (type_identifier)) ; [3, 27] - [3, 28] cpp
                (parameter_declaration ; [3, 30] - [3, 31] cpp
                  type: (type_identifier)))) ; [3, 30] - [3, 31] cpp
            value: (identifier))))))) ; [3, 35] - [3, 42] cpp

See that the friend function with = default got parsed as a declaration, and the default got parsed as a value, not a keyword.

Expected Behavior/Parse Tree

Defaulted friend functions (currently probably only operator== and operator<=>) should get parsed as such.

Repro

(see example above bad tree)