Add required flag to input container

[barbaravaldez]

For #25159

[kisantia]

The accessibility testers request that accessibility issues stay open until they verify the fix (they can test the insiders build when the fix is available), so either remember to reopen the issue after the PR is merged or use a different word in the description so the issue doesn't get auto closed.

[coveralls]

Pull Request Test Coverage Report for Build 7632960265

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.002%) to 41.759%

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Totals
Change from base Build 7629755571:	0.002%
Covered Lines:	30827
Relevant Lines:	69081

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💛 - Coveralls