[Localization] Support an optional object of Localized phrases for Screen Reader announcements

## Context
Currently, all the screen reader announcements for this component are in English and have very generic wording such as "Results hidden". You may want to use more specific verbiage for your component use case, and/or support multiple languages.

## Acceptance Criteria
- [x] Extend the autocomplete API to allow the developer to pass in localized phrases for every Screen Reader announcement
- [ ] If one phrase isn't passed in, fallback to the default already defined (We've got a lot of feedback in the verbiage here.)
- [ ] Create unit tests to ensure these phrases work correctly

Start by locating the autocomplete API and the existing default screen reader announcement phrases. Add coverage for omitted phrases falling back to those defaults, and create unit tests confirming that supplied localized phrases are used for each announcement.

索引モデルが issue の本文から書いたものです。