Add Aria labels to hitsPerPage

[mutherr]

Summary

I was working on improving the accessibility of a project using Instantsearch and noticed that the hits per page widget has no aria label, so I've added it to all three flavors of instantsearch and updated relevant tests

Result

Here's a screenshot of my version with an Aria label present on the hits per page selector.

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Sandbox	Source
example-instantsearch-getting-started	Configuration
example-react-instantsearch-getting-started	Configuration
example-react-instantsearch-next-app-dir-example	Configuration
example-react-instantsearch-next-routing-example	Configuration
example-vue-instantsearch-getting-started	Configuration

[Haroenv]

Thanks! to finalise this we'd want to have this option in translations for React InstantSearch, slots for Vue InstantSearch and templates for InstantSearch.js

[mutherr]

Ok. Where are those defined?

[mutherr]

Quick follow up regarding the vue-instantsearch finalization, as it stands HitsPerPage mirrors the other implementations of aria labeling (ex SortBy.vue) where the template contains a single slot wrapping the entire select element, rather than having slots for individual elements and their attributes. What to your mind does a finalized version of this look like?