fix(material/radio): updating required value should mark for check (#31109)

This change ensures that updates to the required value of the radio
button also mark the component for check, ensuring OnPush compatibility.

(cherry picked from commit fc36e66)

Author: atscott

src/material/radio/radio.ts

@@ -518,6 +518,9 @@ export class MatRadioButton implements OnInit, AfterViewInit, DoCheck, OnDestroy
     return this._required || (this.radioGroup && this.radioGroup.required);
   }
   set required(value: boolean) {
+    if (value !== this._required) {
+      this._changeDetector.markForCheck();
+    }
     this._required = value;
   }