Don't allow adding domains on subprojects

[stsewd]

This action isn't allowed at the form level, it gives a generic error, as it was expecting the UI to block this action, so users won't get this error.

I also noticed that we are blocking the whole list, but we only want to block the "add" action, as users could have had domains already created, we still want users to be able to delete those.

closes #666

[Copilot]

Pull Request Overview

This PR adds a notification message to inform users when a project is a subproject that custom domains must be managed by the superproject, and disables the domain list form in this case.

• Added blocktrans to i18n imports to support translatable messages with variable interpolation
• Added informational message with links when a project has a superproject
• Updated the disabled segment condition to include the superproject check

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[humitos]

🎉

[agjohnson]

In the subproject listing UI, we only display the listing if it's possible to use the listing UI and create subprojects. We should probably do that here instead of just disabling the segment visually.

ext-theme/readthedocsext/theme/templates/projects/projectrelationship_list.html

Lines 10 to 36 in 1831b18

	{% block project_edit_content %}
	{% if superproject %}
	<div class="ui icon message">
	<i class="fa-duotone fa-circle-exclamation icon"></i>
	<div class="content">
	<div class="header">
	{% trans "Nested subprojects are not supported" %}
	</div>
	<p>
	{% blocktrans trimmed with project=superproject.name %}
	This project is already configured as a subproject of {{ project }}.
	{% endblocktrans %}
	</p>
	<p>
	<a href="{% url 'projects_subprojects' project_slug=superproject.slug %}">
	{% blocktrans trimmed with project=superproject.name %}
	View all subprojects of {{ project }}
	{% endblocktrans %}
	</a>
	</p>
	</div>
	</div>
	{% else %}
	{% include "projects/partials/edit/subproject_list.html" with objects=object_list %}
	{% endif %}
	{% endblock %}