Add `{% attrs %}` tag to generate attributes without field

[christophehenry]

The attr filter is nice to append HTML attributes to form fields but it would be nicer being able to also use it without fields like this:

{% attr "data-test-thing:test-value" as attr_dict %}
<section {{ attr_dict }}>
…
</section>

I couldn't find this feature request in the open tickets. Please excuse if this is a duplicate.

[maximbelyayev]

+1. Would be nice if we could {% render_field field attr_dict=attr_dict %}, if attr_dict is provided in context.

Especially for working with django-components where keys in context dict can change, reduces the annoyance to have a million nested if attr, render_fileld, and endif statements and ensure you have every permutation like:

{% if attr %}
    {% if attr1 %}
        {% if attr2 %}
             {% render_field field attr=attr attr1=attr1 attr2=attr2 %}
        {% else %}
             {% render_field field attr=attr attr1=attr1 %}
        {% endif %}
    {% elif attr2 %}
        {% render_field field attr=attr attr2=attr2 %}
    {% else %}
        {% render_field field attr=attr %}
{% elif attr1 %}
    {% if attr2 %}
        {% render_field field attr1=attr1 attr2=attr2 %}
    {% else %}
        {% render_field field attr1=attr1 %}
{% elif attr2 %}
    {% render_field field attr2=attr2 %}
{% endif %}