N°7995 - Allow to redefine portal twig template for all bricks in a portal

[steffunky]

Base information

Question	Answer
Related to a SourceForge thead / Another PR / Combodo ticket?	N°7995
Type of change?	Enhancement

Objective

When redefining a brick template, you need to overload the <template> for every brick definition.
It works well for one specific iTop, but as we plan to release an extension bringing the 3.3.0 portal design compatible with iTop 3.2.1+, we need to be able to overload templates for all bricks in a portal without overloading every brick definition

Proposed solution

This pull request use the <template> defined in the portal properties, allowing it to define new default templates that bricks will take into account if they do not have a specific template in their definition.

Example of a customization that'll affect every BrowseBrick in a portal:

  <module_design xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" id="itop-portal" xsi:type="portal">
  <properties>
    <templates>
      <template id="Combodo\iTop\Portal\Brick\BrowseBrick:page" _delta="define">itop-custom-browse-brick/templates/page.html.twig</template>
    </templates>
  </properties>
  </module_design>

Checklist before requesting a review

• I have performed a self-review of my code
• I have tested all changes I made on an iTop instance
• I have added a unit test, otherwise I have explained why I couldn't
• Is the PR clear and detailed enough so anyone can understand digging in the code?