PIM-1850 Ask users to choose the attribute type before creating an attribute

This fixes several issues related to dynamic changing of the attribute form.

Bug fix: yes
Feature addition: no
Backwards compatibility break: no
Unit test passes: yes
Specs passes: yes
Behat scenario passes: yes
Checkstyle issues: no
ChangeLog updated: yes
Documentation PR: ~
Fixes the following jira:
 - PIM-1850