`A2-7-3`: Support doxygen grouping

[lcartey]

Affected rules

• A2-7-3

Description

Doxygen allows you to provide documentation for a "group" of declarations at once - for example, for all overloads of a function. We should consider this when determining whether a declaration is documented.

Example

Examples here: https://www.doxygen.nl/manual/grouping.html, including:

class Memgrp_Test
{
  public:
    ///@{
    /** Same documentation for both members. Details */
    void func1InGroup1();
    void func2InGroup1();
    ///@}
 
    /** Function without group. Details. */
    void ungroupedFunction();
    void func1InGroup2();
  protected:
    void func2InGroup2();
};