NXP-13029: add 'tenant_administrators_widget.xhtml' template, a copy of 'user_suggestion_widget_template.xhtml'
NXP-13029: add validator to 'tenant_administrators_widget.xhtml' template to avoid the current user to remove himself from the tenant administrators; use the new template for the 'tenant_administrators' widget
NXP-13206: add French labels; cleanup messages*properties files