(core) Moving client and common tests to core

Summary:
- Moved /test/client and /test/common to core.
- Moved two files (CircularArray and RecentItems) from app/common to core/app/common.
- Moved resetOrg test to gen-server.
- `testrun.sh` is now invoking common and client test from core.
- Added missing packages to core's package.json (and revealed underscore as it is used in the main app).
- Removed Coord.js as it is not used anywhere.

Test Plan: Existing tests

Reviewers: paulfitz

Reviewed By: paulfitz

Subscribers: paulfitz

Differential Revision: https://phab.getgrist.com/D3590

app/common/RecentItems.js

@@ -0,0 +1,50 @@
+/**
+ * RecentItems maintains a list of maxCount most recently added items.
+ * If an existing item is added, it is moved to the end of the list.
+ *
+ * @constructor
+ * @param {Int} options.maxCount - The maximum number of objects that will be maintained.
+ * @param {Function} options.keyFunc -  Function that returns a key identifying an item;
+ * If an item is added with an existing key, it replaces the previous item in the list but is
+ * moved to the end of the list.  Defaults to the identity function.
+ * @param {Array} options.intialItems - A list of items to populate the list on initialization
+ */
+
+class RecentItems {
+  constructor(options) {
+    this._items = new Map();
+    this._maxCount = options.maxCount || 0;
+    this._keyFunc = options.keyFunc || (item => item);
+    if (options.intialItems) this.addItems(options.intialItems);
+  }
+
+  addItem(item) {
+    // Map maintains entries in the order of insertion, so by deleting and reinserting an entry,
+    // we move it to the end of the list.
+    this._items.delete(this._keyFunc(item));
+    this._items.set(this._keyFunc(item), item);
+    // Now that the list is correctly ordered we may need to remove the oldest entry which is
+    // the first item.
+    if (this._items.size > this._maxCount && this._maxCount !== 0) {
+      this._items.delete(this._items.keys().next().value);
+    }
+  }
+
+  addItems(items) {
+    items.forEach(item => {
+      this.addItem(item);
+    });
+  }
+
+  /**
+   * Returns a list of the current items in the map.  The list is starts with oldest
+   * added item and ends with the most recently inserted.
+   *
+   * @returns {Array} A list of items.
+   */
+  listItems() {
+    return Array.from(this._items.values());
+  }
+}
+
+module.exports = RecentItems;