fix(back-button): screen readers correctly announce the back button text

[liamdebeasi]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Build (npm run build) was run locally and any changes were pushed
• Lint (npm run lint) has passed locally and any fixes were made for failures

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Issue Number: #21043

What is the new behavior?

• Added aria-hidden to back button icon and back button text element
• Added aria-label to parent button element. Since the icon is sometimes decorative sometimes semantic, I think it makes sense to just place the aria-label on the parent button rather than add logic for the icon and label.

Does this introduce a breaking change?

• Yes
• No

Other information

[RenAlbiorix]

In which version this is fixed? I facing this issue in ionic 4

[liamdebeasi]

This was fixed in v5.1.0.