feat(core): add support for ShadowDOM v1 (#24718)

add a new ViewEncapsulation.ShadowDom option that uses the v1 Shadow DOM API to provide style encapsulation.

PR Close #24718

tools/public_api_guard/core/core.d.ts

@@ -932,6 +932,7 @@ export declare enum ViewEncapsulation {
     Emulated = 0,
     Native = 1,
     None = 2,
+    ShadowDom = 3,
 }
 
 export declare abstract class ViewRef extends ChangeDetectorRef {