fix(material/input): show required asterisk when using required validator

[crisbeto]

Resolves the long-standing issue where the required asterisk wasn't being shown in the form field label when using the required validator from Forms.

Note: these changes target v13, because the hasValidator API was introduced in 12.2.0.

Fixes #2574.

[mmalerba]

LGTM

[devversion]

🎉

[jlcarmer]

This is a breaking change incompatible with the material spec. No asterisk probably should have been the default

https://material.io/components/text-fields#:~:text=Required%20text%20indicator

[crisbeto]

This change is primarily for consistency. Before it, you'd get the asterisk with ngModel, but not with formControl, but they should behave the same.

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