(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/ui/ViewLayoutMenu.ts

@@ -0,0 +1,25 @@
+import {allCommands} from 'app/client/components/commands';
+import {ViewRec, ViewSectionRec} from 'app/client/models/DocModel';
+import {testId} from 'app/client/ui2018/cssVars';
+import {menuDivider, menuItemCmd} from 'app/client/ui2018/menus';
+import {dom} from 'grainjs';
+
+/**
+ * Returns a list of menu items for a view section.
+ */
+export function makeViewLayoutMenu(viewModel: ViewRec, viewSection: ViewSectionRec, isReadonly: boolean) {
+  return [
+    dom.maybe((use) => ['detail', 'single'].includes(use(viewSection.parentKey)), () =>
+      menuItemCmd(allCommands.editLayout, 'Edit Card Layout',
+        dom.cls('disabled', isReadonly))),
+
+    menuItemCmd(allCommands.deleteSection, 'Delete widget',
+      dom.cls('disabled', viewModel.viewSections().peekLength <= 1 || isReadonly),
+      testId('section-delete')),
+    menuDivider(),
+
+    menuItemCmd(allCommands.viewTabOpen, 'Widget options', testId('widget-options')),
+    menuItemCmd(allCommands.sortFilterTabOpen, 'Advanced Sort & Filter'),
+    menuItemCmd(allCommands.dataSelectionTabOpen, 'Data selection')
+  ];
+}