MySqlDateTime should implement IConvertible

[fish-li]

The same testcase,
MySqlConnector is failed, MySql.Data works!

[TestMethod]
public void Test_DateTime_DataType()
{
    string connectionString1 = "Server=FishDbServer;Database=MyNorthwind;Uid=user1;Pwd=qaz1@wsx";
    string connectionString2 = "Server=FishDbServer;Database=MyNorthwind;Uid=user1;Pwd=qaz1@wsx;Allow Zero Datetime=True;Convert Zero Datetime=True;";

    object result1, result2;

    using(MySqlConnection conn1 = new MySqlConnection(connectionString1)){
        conn1.Open();

        MySqlCommand command1 = conn1.CreateCommand();
        command1.CommandText = "select now()";
        result1 = command1.ExecuteScalar();
    }


    using( MySqlConnection conn2 = new MySqlConnection(connectionString2) ) {
        conn2.Open();

        MySqlCommand command2 = conn2.CreateCommand();
        command2.CommandText = "select now()";
        result2 = command2.ExecuteScalar();
    }

    Assert.AreEqual(typeof(DateTime), result1.GetType());

    // set "Allow Zero Datetime=True", result is MySqlDateTime
    Assert.AreEqual(typeof(MySql.Data.Types.MySqlDateTime), result2.GetType());


    DateTime time1 = (DateTime)Convert.ChangeType(result1, typeof(DateTime));

    // MySqlConnector throw error: System.InvalidCastException: Object must implement IConvertible.
    // MySql.Data, It works!
    DateTime time2 = (DateTime)Convert.ChangeType(result2, typeof(DateTime));

    // MySqlConnector
    // public struct MySqlDateTime : IComparable

    // MySql.Data
    // public struct MySqlDateTime : IMySqlValue, IComparable, IConvertible

    Assert.AreEqual(time1, time2);
}

[bgrainger]

Implement using IConvertible.ToDateTime() => GetDateTime();; all other conversions should throw InvalidCastException.

[bgrainger]

Added in 0.64.0.