(core) move client code to core

Summary:
This moves all client code to core, and makes minimal fix-ups to
get grist and grist-core to compile correctly.  The client works
in core, but I'm leaving clean-up around the build and bundles to
follow-up.

Test Plan: existing tests pass; server-dev bundle looks sane

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2627

app/client/components/ClientScope.ts

@@ -0,0 +1,55 @@
+import * as dispose from 'app/client/lib/dispose';
+import {Storage} from 'app/plugin/StorageAPI';
+import {checkers} from 'app/plugin/TypeCheckers';
+import {Rpc} from 'grain-rpc';
+
+/**
+ * Implementation of interfaces whose lifetime is that of the client.
+ */
+export class ClientScope extends dispose.Disposable {
+  private _pluginStorage = new Map<string, Storage>();
+
+  public create() {
+    // nothing to do
+  }
+
+  /**
+   * Make interfaces available for a plugin with a given name.  Implementations
+   * are attached directly to the supplied rpc object.
+   */
+  public servePlugin(pluginId: string, rpc: Rpc) {
+    // We have just one interface right now, storage.  We want to keep ownership
+    // of storage, so it doesn't go away when the plugin is closed.  So we cache
+    // it.
+    let storage = this._pluginStorage.get(pluginId);
+    if (!storage) {
+      storage = this._implementStorage();
+      this._pluginStorage.set(pluginId, storage);
+    }
+    rpc.registerImpl<Storage>("storage", storage, checkers.Storage);
+  }
+
+  /**
+   * Create an implementation of the Storage interface.
+   */
+  private _implementStorage(): Storage {
+    const data = new Map<string, any>();
+    return {
+      getItem(key: string): any {
+        return data.get(key);
+      },
+      hasItem(key: string): boolean {
+        return data.has(key);
+      },
+      setItem(key: string, value: any) {
+        data.set(key, value);
+      },
+      removeItem(key: string) {
+        data.delete(key);
+      },
+      clear() {
+        data.clear();
+      },
+    };
+  }
+}