Block editor store: also attach private APIs to old store descriptor

As a workaround, until #39632 is merged, make sure that private actions
and selectors can be unlocked from the original store descriptor (the
one created by `createReduxStore`) and not just the one registered in
the default registry (created by `registerStore`).

Without this workaround, specific setups will unexpectedly fail, such as
the action tests in the `reusable-blocks` package, due to the way that
those tests create their own registries in which they register stores
like `block-editor`.

Context: #51145 (comment)

Props jsnajdr

packages/block-editor/src/store/index.js

@@ -43,3 +43,13 @@ const registeredStore = registerStore( STORE_NAME, {
 } );
 unlock( registeredStore ).registerPrivateActions( privateActions );
 unlock( registeredStore ).registerPrivateSelectors( privateSelectors );
+
+// TODO: Remove once we switch to the `register` function (see above).
+//
+// Until then, private functions also need to be attached to the original
+// `store` descriptor in order to avoid unit tests failing, which could happen
+// when tests create new registries in which they register stores.
+//
+// @see https://github.com/WordPress/gutenberg/pull/51145#discussion_r1239999590
+unlock( store ).registerPrivateActions( privateActions );
+unlock( store ).registerPrivateSelectors( privateSelectors );

packages/block-editor/src/store/private-actions.js

@@ -161,19 +161,7 @@ export const privateRemoveBlocks =
 		// register using `toggleRemovalPromptSupport()`.
 		//
 		// @see https://github.com/WordPress/gutenberg/pull/51145
-		if (
-			! forceRemove &&
-			// FIXME: Without this existence check, the unit tests for
-			// `__experimentalDeleteReusableBlock` in
-			// `packages/reusable-blocks/src/store/test/actions.js` fail due to
-			// the fact that the `registry` object passed to the thunk actions
-			// doesn't include this private action. This needs to be
-			// investigated to understand whether it's a real smell or if it's
-			// because not all store code has been updated to accommodate
-			// private selectors.
-			select.isRemovalPromptSupported &&
-			select.isRemovalPromptSupported()
-		) {
+		if ( ! forceRemove && select.isRemovalPromptSupported() ) {
 			const blockNamesForPrompt = new Set();
 
 			// Given a list of client IDs of blocks that the user intended to

packages/block-editor/src/store/test/actions.js

@@ -618,6 +618,7 @@ describe( 'actions', () => {
 			const select = {
 				getBlockRootClientId: () => undefined,
 				canRemoveBlocks: () => true,
+				isRemovalPromptSupported: () => false,
 			};
 			const dispatch = Object.assign( jest.fn(), {
 				selectPreviousBlock: jest.fn(),
@@ -728,6 +729,7 @@ describe( 'actions', () => {
 			const select = {
 				getBlockRootClientId: () => null,
 				canRemoveBlocks: () => true,
+				isRemovalPromptSupported: () => false,
 			};
 			const dispatch = Object.assign( jest.fn(), {
 				selectPreviousBlock: jest.fn(),
@@ -752,6 +754,7 @@ describe( 'actions', () => {
 			const select = {
 				getBlockRootClientId: () => null,
 				canRemoveBlocks: () => true,
+				isRemovalPromptSupported: () => false,
 			};
 			const dispatch = Object.assign( jest.fn(), {
 				selectPreviousBlock: jest.fn(),