[BP Nouveau Request] BP_Group_Extension->widget_diplay() is never reachable

[imath]

The action added to 'groups_custom_group_boxes' that calls the Group Class widget_display method is inside an if statement that is always false. See below

if ( ! bp_current_action() && bp_is_current_action( 'home' ) ) {}

It's not possible for the current action to be home and nothing at the same time :)

So i'd suggest to use the bp_is_group_home() template tag instead, to give it a chance to be used in case the theme is using the bp_custom_group_boxes() template tag.

[imath]

In 10905:

Groups: Make sure BP_Group_Extension::widget_display() can be used

On the single item home (eg: a custom front template), it will now be possible to use bp_custom_group_boxes() to get the content provided by the Group extensions in their widget.

2 unit tests are checking this only happens when on the Groups single item home.

Fixes #7131