Clarify filters display in widget

[Archidoit]

Reproductible steps

Go to a custom dashboard. Create a widget. Select a type of widget (ex: vertical bar), and the 'Knowledge'. Select some filters, dynamic filters and source filters.

To do

In the screen of filters edition of widgets, add some precisions

Design

Seen with @Jipegien and @richard-julien : we should separate the 3 types of filters (grey, orange, green), and add some short description before each filters to explain their behavior