[Feature] Support for parsing comment tag

[Adamska1008]

Background

Although comment tags do not affect the content of an XML document, parsing them is a standard feature in almost all XML parsers. Implementing this feature in myxml will ensure compatibility and completeness, making the library more robust.

Feature Description

• In element.hpp: Create a Comment class as a subclass of the Node class. This class should have functionalities similar to the Text class, allowing comments to be treated as a specific type of node within the DOM.
• In parser.hpp: There's no need to create a separate method specifically for parsing comment tags. Instead, enhance the Parser::parseTag method to recognize and handle comment tags. In Parser::ParseElement, when a comment tag is detected, it should be added as a child node of the current element.