Move shared components to a packages/ directory (#30962)

* Move shared components to a packages/ directory

so they can be publish more sensibly

* Iterate towards split out shared-components module

 * Move shared component source into src/ subdir
 * Fix up imports
 * Include shared components in babel-ing (again)

* Remove now unused dependencies

* Update import in storybook preview

* ...except of course they aren't unused

if we import the shared components by source

* Ignore shared components deps

* Add shared-components to i18n paths

and upgrade web-i18n to version that supports doing so

* Move storybook stuff to shared-components

* Seems we don't need this anymore...

* Remove unused deps

and remove storybook plugin from eslint

* Presumably working-directory is only valid on run steps

* Ignore dep & run prettier

* Prettier on knips.ts

* Hopefully run in right dir

* Remember how to software write

* Okay... how about THIS way?

* Oh right, they were git ignored. Sigh.

* Add concurrently

* Ignore in knip

* Better?

* Paaaaaaaackageeeeeeees

* More packages

* Move playwright snapshots

* Still need a custom snapshots dir

* Add eslint back

* Oh, now knip sees them

* Fix another import

* Don't lint shared-components with everything else

Okay, eslint & tsconfig are tied too closely for this to work and
running tsc on the shared components will need its deps installing

* Maybe lint shared components

please?

* Not quite

* Remove storybook again

Re-check if it does work without it

* Remove storybook eslint plugin

as we're not linting storybook here anymore

* Remove this too

* We do need it here though

packages/shared-components/src/useViewModel.ts

@@ -0,0 +1,21 @@
+/*
+Copyright 2025 New Vector Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { useSyncExternalStore } from "react";
+
+import { type ViewModel } from "./ViewModel";
+
+/**
+ * A small wrapper around useSyncExternalStore to use a view model in a shared component view
+ * @param vm The view model to use
+ * @returns The current snapshot
+ */
+export function useViewModel<T>(vm: ViewModel<T>): T {
+    // We need to pass the same getSnapshot function as getServerSnapshot as this
+    // is used when making the HTML chat export.
+    return useSyncExternalStore(vm.subscribe, vm.getSnapshot, vm.getSnapshot);
+}