[BUG] Wrong constexpr initialization

[ekherit]

Description
Operator "==" works fine for initializing constexpr parameters for simple types. However, incorrect code is generated for types that initialized via initializer_list or for types with complex (with more then one parameters) constructor.

To reproduce

    x : int = 1;
    xc : int == 1;
    
    a : std::array = (1,2,3);
    ac : std::array == (4,5,6);

    v: std::vector = (1,2,3);
    vc: std::vector == (1,2,3);    

    t : mytype = (5,6,7);
    tc : mytype == (5,6,7);

Generates

    int x {1}; 
    int constexpr xc = 1; //OK
    
    std::array a {1, 2, 3}; 
    std::array constexpr ac = (4, 5, 6); //BUG

    std::vector v {1, 2, 3}; 
    std::vector constexpr vc = (1, 2, 3); //BUG

    mytype t {5,6,7}; 
    mytype constexpr tc = (5, 6, 7); //BUG

Expected result

    int x {1}; 
    int constexpr xc = 1;
    
    std::array a {1, 2, 3}; 
    std::array constexpr ac{4, 5, 6};

    std::vector v {1, 2, 3}; 
    std::vector constexpr vc{1, 2, 3};

    mytype t {5,6,7}; 
    mytype constexpr tc{5,6,7};

Additional context
Trunk version of cppfront at godbolt.org

[JohelEGP]

This is #699.