[IMP] web: add a badge based widget for selection fields

This commit introduces a new widget to be used for selection-based fields.
Valid choices are displayed using rectangular badges and not like the
standard list. This widget is valid for selection and many2one fields
like selection or radio widgets.

Co-authored-by: Siddarth Gajjar <sga@odoo.com>
Co-authored-by: Mohammed Shekha <msh@openerp.com>

doc/reference/javascript_reference.rst

@@ -1756,6 +1756,16 @@ Relational fields
         <field name="recommended_activity_type_id" widget="radio"
             options="{'horizontal':true}"/>
 
+- selection_badge (FieldSelectionBadge)
+    This is a subfield of FieldSelection, but specialized to display all the
+    valid choices as rectangular badges.
+
+    - Supported field types: *selection, many2one*
+
+    .. code-block:: xml
+
+        <field name="recommended_activity_type_id" widget="selection_badge"/>
+
 - many2one (FieldMany2One)
     Default widget for many2one fields.