Recursively check label children for input control

[nsimonson]

a11y-label-has-associated-control was only checking direct children. This would cause a false positive when the label was abstracted to a component or the input control was nested in other tags.

Fixes #5300
Fixes #5528

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Tests

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[sahinf]

Will this fix be merged anytime?

[tanhauhau]

Related #6442