(core) move home server into core

Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552

app/server/lib/DocPluginData.ts

@@ -0,0 +1,32 @@
+import {Promisified} from 'app/common/tpromisified';
+import {Storage} from 'app/plugin/StorageAPI';
+import {DocStorage} from 'app/server/lib/DocStorage';
+
+/**
+ * DocPluginData implements a document's `Storage` for plugin.
+ */
+export class DocPluginData implements Promisified<Storage> {
+  constructor(private _docStorage: DocStorage, private _pluginId: string) {
+    // nothing to do here
+  }
+  public async getItem(key: string): Promise<any> {
+    const res = await this._docStorage.getPluginDataItem(this._pluginId, key);
+    if (typeof res === 'string') {
+      return JSON.parse(res);
+    }
+    return res;
+  }
+  public hasItem(key: string): Promise<boolean> {
+    return this._docStorage.hasPluginDataItem(this._pluginId, key);
+  }
+  public setItem(key: string, value: any): Promise<void> {
+    return this._docStorage.setPluginDataItem(this._pluginId, key, JSON.stringify(value));
+  }
+  public removeItem(key: string): Promise<void> {
+    return this._docStorage.removePluginDataItem(this._pluginId, key);
+  }
+  public clear(): Promise<void> {
+    return this._docStorage.clearPluginDataItem(this._pluginId);
+  }
+
+}