[Image v3] Add copyright support

[renow-luxembourg]

Feature Request

Is your feature request related to a problem? Please describe.
Photographs, illustrations and other images will generally be protected by copyright as artistic works.
We would like to add some copyright/credits information under each image (in addition of the caption) with a différent style.
For the moment in the DAM we can define a caption (titleValueFromDAM) and an alternative text (altValueFromDAM)

Describe the solution you'd like
The easier solution for us will be to add a new field in the DAM named copyright.
And display it like the caption :

<span class="cmp-image__title" itemprop="caption">Image caption</span>
<span class="cmp-image__credits" itemprop="caption">©Image copyright</span>

This will allow us to customize the style with css.

Are there alternatives?
An other alternative is to allow HTML code in the title field of the DAM. The result will be something like :

<span class="cmp-image__title" itemprop="caption">
  <span class="caption">Image caption</span>
  <span class="credits">©Image copyright</span>
</span>

But it require for the redactor to learn a bit of HTML

[ky940819]

There are already fields in the DAM for license information:

• Creator
• Contributor
• Copyright owner
• Usage terms
• Expires

An ideal solution might be something along the lines of:

• Add a section to the policy dialog to allow template / policy maintainers to enable license information to be shown.
  • The default for this should be disabled, such that the change is backwards-compatible.
  • If enabled, then the template / policy maintainers should be able to select which fields are shown (from the above list).
  • Ideally, each field could be enabled or disabled in the policy
• If this feature has been enabled, then the edit dialog should show a text area for each field, as well as an "inherit from DAM" checkbox - consistent with how it already works for image descriptions
• If this feature has been enabled, then the html should contains a license section; each field that has a non-blank value should be rendered

The rendered output might look something like:

<span class="cmp-image__title" itemprop="caption">Image caption</span>
<div class="cmp-image__license" itemprop="caption">
    <div>
        <span class="cmp-image__license-label">Copyright Owner</span>
        <span class="cmp-image__license-value">User input or DAM value</span>
    </div>
    <div>
        <span class="cmp-image__license-label">Terms of Usage</span>
        <span class="cmp-image__license-value">User input  or DAM value</span>
    </div>
    <!-- ....etc ->
</div>

As the template / policy maintainer, in combination with the author using the component, would have full control over what fields are shown, and could style the section as they see fit