refactor(@angular-devkit/core): deprecate PartiallyOrderedSet

The PartiallyOrderedSet class was only used to handle dependencies in SchemaRegistry transforms. Since that feature is now deprecated, this class is also marked as deprecated.

Author: clydin

goldens/public-api/angular_devkit/core/index.api.md

@@ -553,7 +553,7 @@ function oneLine(strings: TemplateStringsArray, ...values: any[]): string;
 // @public (undocumented)
 function parseJsonPointer(pointer: JsonPointer): string[];
 
-// @public (undocumented)
+// @public
 export class PartiallyOrderedSet<T> {
     // (undocumented)
     [Symbol.iterator](): IterableIterator<T, undefined, unknown>;

packages/angular_devkit/core/src/utils/partially-ordered-set.ts

@@ -19,6 +19,9 @@ export class CircularDependencyFoundException extends BaseException {
   }
 }
 
+/**
+ * @deprecated Use standard arrays and ensure correct insertion order instead.
+ */
 export class PartiallyOrderedSet<T> {
   private _items = new Map<T, Set<T>>();