Fix referrers display to show only current referrers.

Updated the view to loop through current referrers in the accompanying period. Added new method `getReferrersHistoryCurrent` to the entity to filter and return only active referrers, ensuring correct display in the UI. Also included documentation for better code clarity.

src/Bundle/ChillPersonBundle/Resources/views/AccompanyingCourseWork/_item.html.twig

@@ -83,10 +83,10 @@
                 </div>
                 <div class="wl-col list">
                     {%- if w.referrers|length > 0 -%}
-                        {% for r in w.referrersHistory %}
+                        {% for r in w.referrersHistoryCurrent %}
                             <span class="wl-item">
                                 <span class="badge-user">{{ r.user|chill_entity_render_box({'at_date': r.startDate}) }}</span>
-                                {% if not loop.last %}, {% endif %}
+                                {%- if not loop.last %}, {% endif %}
                             </span>
                         {% endfor %}
                     {% else %}