Placeholder ticket for everything related to screenreaders reading out loud what's going on in the #VisualEditor template editor.
* When I, as a screenreader user, navigate the right content area of the template dialog, I want to understand where I am, and what the meaning of the elements is. Especially: Template names and parameter names should not just be read as they are, but announced as e.g. "template 'infobox river'" or "edit parameters of 'infobox river'". Individual parameters might be announced as e.g. "(parameter) 'name' of/in 'infobox river'". **(TBD)**
* When I navigate the sidebar, every element should be properly announced. Most notably: The list of parameter (being a single tab target) must be announced with e.g. "parameters available for 'infobox river', use cursor keys and space to toggle". **(TBD)**
* When I press enter in the sidebar, the focus jumps to the corresponding template header or individual parameter on the right. The first thing the screenreader should read is not necessarily the name of the template or parameter. That would be redundant, assuming this was the last thing that was read before leaving the sidebar. Still I, as a screenreader user, want to understand where I am. The screenreader should announce these positions somehow, e.g. "edit parameters of 'infobox river'" (note this was originally part of T285323). **(TBD)**
* ~~Required parameters are represented as disabled checkboxes in the sidebar. Make sure screenreader users can understand this. Possibly remove the checkbox. Possibly make use of OO.ui.mixin.RequiredElement (sets `aria-required`, see https://gerrit.wikimedia.org/r/711145 ).~~ From https://stackoverflow.com/q/34300154#comment85584639_34300154: //"For checkboxes, regardless if checked or not a value is passed to through the form. If you want to communicate that the user must check a checkbox to proceed / submit, then such a message should be associated through us of the aria-describedby attribute pointing to a text container (via that container's ID attribute)."//
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Other things we should not forget (not necessarily part of this ticket):
* It must be possible to select a part in a multi-part template with space/enter (similar to selecting a parameter). The selection should stay when I leave the sidebar. When I navigate to the bottom toolbar and use it's buttons, they interact with the selected part.
* Possibly assign a keyboard shortcut to the bottom toolbar.
* Make it possible to press {key Ctrl Shift Up} and {key Ctrl Shift Down} (Ctrl + Shift + Up/Down, same as in e.g. the PHPStorm IDE) to move elements in a multi-part template around.
* Talk about a keyboard shortcut like e.g. {key Ctrl Del} to delete a part from a multi-part template.