Append visually hidden group title to the element template label

[rpkoller]

Is your feature request related to a problem? Please describe
If you are stepping through the list of available element templates as a screen reader user and you have a group of lets say more than 20 templates within a single group it might be difficult to remember in which context aka group you currently are. the smaller the working memory the more challenging the endeavor.

Describe the solution you'd like
lets say you have the following setup with two groups and five templates

group 1
  one template
  another template
  yet another template
group 2
  a template
  one template

i would suggest to append the group title in a visually hidden span.

one template<span class="visually-hidden"> for group 1</span>
or as an alternativ
one template<span class="visually-hidden">: group 1</span>

that way the most important information aka the template name is front loaded but at any point the information which group a template belongs to is available afterwards and could be skipped at any point.
but there is still the issue about how those templates are announced or better not announced. for that i have to open up a separate issue.

Describe alternatives you've considered

Additional context

[nikku]

Transfered this to the core as our create/append/replace anything UI suffers the same issue.

[nikku]

@rpkoller I wonder how this interacts with #735, i.e. the fact that we don't properly group elements in an accessible manner.

If elements were properly linked to a "parent", the group, would that fix things? Or can we attach a meaningful title to elements?