Action templates all inherit from action_base.html, which has two

modes:


Presenting top-level actions, which have a rb-c-actions__action

   container with an ID, visibility attributes, and more.


Presenting inner actions, which don't have a container but do manage

   an ID and visibility attributes.


There was no control over that container element in templates, and the

attribute and visibility management was a bit all over the place. Any

child of a group was invisible by default, which is really only

appropriate for the default style of non-Ink menu item.
The old template made it a real challenge to create maintainable

actions, and was impacting the new sidebar action support, so it's been

reworked.
The new template defines all the following blocks for various bits of

control:


action_is_visible: Controls visibility of the action. Can contain

true or any other value for false. Defaults to the action's

visible state.


action_has_container: Controls the presence of a default container

  element. Defaults to true if it's a top-level action.


action_container_tag: The HTML tag for the container element.

  Defaults to li.


action_container_css_class: Any additional CSS classes for the

  container element.


action_attrs: DOM attributes suitable for the inner element.

  Defaults to including an ID and visibility attributes if

action_has_container=False.


action_container_attrs: DOM attributes suitable for the container

  element. Defaults to including an ID and visibility attributes if

action_has_container=True.


action_container_role: The role for the container element. Defaults

  to presentation.


action_container_start: The start tag for the container element.


action_container_end: The end tag for the container element.


action_content: The content of the action.


There are some structural changes that are important for consistency

with flexible rendering:


Action IDs are now always set for the inner element, and not the

   container element. This provides consistency. Before, it was

   dependent on where the action was rendered.


Because of that, actions should now be wrapped in one element,

   regardless of a container, so it may have an ID associated. The menu

   action, for instance, now has an inner wrapper element for the ID

   with a label.


Visibility is still on the container action for top-level actions,

   and the inner element for inner actions. The JavaScript still manages

   this properly. Actions are no longer hidden by default if they're

   inside another group.


The visibility changes uncovered a bug in menu items where, due

   to being directly parented to the rb-c-actions__action container

   element of the parent menu, they fetched the wrong visibility

   element. Since they're not intended to be shown (menus get rebuilt

   with their information), we now wrap them in a hidden div so they

   never display.


The menu template is adapted to support the new functionality and to

cover the use cases we were special-casing everywhere. The custom

Archive and Account menus have been moved over to use the improved

template. This all needed to be done in the same change due to the

impact on these templates.
This change requires the new changes up for review in Djblets 5.3 for

{% definevar as_type= %}.

Tested the appearance and interactivity of all actions, with close

attention paid to the various menu actions.
Tested new in-progress action renderers for sidebars.
Unit tests pass.