(core) Context menu for cards.

Summary:
User was not able to delete cards. This patch introduces a context menu for cards, analogous to the one available for rows on a GridView.

Changes:
- Row numbers on a GridView have the same icon as on columns to make context menu more discoverable.
- Context menu for rows and columns, when activated, didn't switch section in rare conditions (i.e. when the section had 2 or more columns selected, one of which had the same rowId as a column in the section that the user switched from).
- Card list layout and a single card layout has the same context menu as in a GridView, available by pressing the context menu button.

Test Plan: Browser tests

Reviewers: dsagal, paulfitz

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2870

app/client/ui/GridViewMenus.ts

@@ -31,42 +31,6 @@ export function ColumnAddMenu(gridView: IView, viewSection: IViewSection) {
       }, `Show column ${col.label()}`))
   ];
 }
-
-interface IRowContextMenu {
-  disableInsert: boolean;
-  disableDelete: boolean;
-  isViewSorted: boolean;
-}
-
-export function RowContextMenu({ disableInsert, disableDelete, isViewSorted }: IRowContextMenu) {
-  const result: Element[] = [];
-  if (isViewSorted) {
-    // When the view is sorted, any newly added records get shifts instantly at the top or
-    // bottom. It could be very confusing for users who might expect the record to stay above or
-    // below the active row. Thus in this case we show a single `insert row` command.
-    result.push(
-      menuItemCmd(allCommands.insertRecordAfter, 'Insert row',
-        dom.cls('disabled', disableInsert)),
-    );
-  } else {
-    result.push(
-      menuItemCmd(allCommands.insertRecordBefore, 'Insert row above',
-        dom.cls('disabled', disableInsert)),
-      menuItemCmd(allCommands.insertRecordAfter, 'Insert row below',
-        dom.cls('disabled', disableInsert)),
-    );
-  }
-  result.push(
-    menuDivider(),
-    menuItemCmd(allCommands.deleteRecords, 'Delete',
-      dom.cls('disabled', disableDelete)),
-  );
-  result.push(
-    menuDivider(),
-    menuItemCmd(allCommands.copyLink, 'Copy anchor link'));
-  return result;
-}
-
 interface IMultiColumnContextMenu {
   // For multiple selection, true/false means the value applies to all columns, 'mixed' means it's
   // true for some columns, but not all.