fix(material/chips): added role presentation to mat-chip host

added role presentation to mat-chip host so that mobile SR users do not have to
double swipe to traverse chip

fixes b/286286473

src/material/chips/chip-row.spec.ts

@@ -102,7 +102,7 @@ describe('MDC-based Row Chips', () => {
       });
 
       it('should have the correct role', () => {
-        expect(chipNativeElement.getAttribute('role')).toBe('row');
+        expect(chipNativeElement.getAttribute('role')).toBe('presentation');
       });
 
       it('should be able to set a custom role', () => {

src/material/chips/chip.ts

@@ -280,6 +280,7 @@ export class MatChip implements OnInit, AfterViewInit, AfterContentInit, DoCheck
     this._isBasicChip =
       element.hasAttribute(this.basicChipAttrName) ||
       element.tagName.toLowerCase() === this.basicChipAttrName;
+    this.role = 'presentation';
   }
 
   ngAfterViewInit() {