WSTEAM1-1027 Uploader File Upload Live Region and aria Labels

[HarveyPeachey]

Resolves JIRA WSTEAM1-1027

Overall changes

Adds a Live region component that the file uploader will send text to, to be read out by the screen reader. Adds aria-required and aria-invalid logic, for the File field.

Code changes

• Adds a LiveRegion component and LiveRegionContext for Live region re-usability
• Updates the File in validateFunctions, to cater for invalid and required logic
• Adds copy for extra text that will be read out by screen readers, these will need translations eventually

Testing

1. Visit http://localhost.bbc.com:7081/somali/send/u130092370?renderer_env=test
2. Make sure logic adheres to what aria labels are added
3. Check when adding and removing files that the live region text updates

Helpful Links

Add Links to useful resources related to this PR if applicable.

Coding Standards

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