(core) Forms Improvements

Summary:
 - Forms now have a reset button.
 - Choice and Reference fields in forms now have an improved select menu.
 - Formula and attachments column types are no longer mappable or visible in forms.
 - Fields in a form widget are now removed if their column is deleted.
 - The preview button in a published form widget has been replaced with a view button. It now opens the published form in a new tab.
 - A new share menu for published form widgets, with options to copy a link or embed code.
 - Forms can now have multiple sections.
 - Form widgets now indicate when publishing is unavailable (e.g. in forks or unsaved documents).
 - General improvements to form styling.

Test Plan: Browser tests.

Reviewers: jarek

Reviewed By: jarek

Subscribers: paulfitz

Differential Revision: https://phab.getgrist.com/D4203

app/client/widgets/CurrencyPicker.ts

@@ -35,7 +35,7 @@ export function buildCurrencyPicker(
   // Create a computed that will display 'Local currency' as a value and label
   // when `currency` is undefined.
   const valueObs = Computed.create(owner, (use) => use(currency) || defaultCurrencyLabel);
-  const acIndex = new ACIndexImpl<ACSelectItem>(currencyItems, 200, true);
+  const acIndex = new ACIndexImpl<ACSelectItem>(currencyItems, {maxResults: 200, keepOrder: true});
   return buildACSelect(owner,
     {
       acIndex, valueObs,

app/client/widgets/FieldBuilder.ts

@@ -34,6 +34,7 @@ import * as UserType from 'app/client/widgets/UserType';
 import * as UserTypeImpl from 'app/client/widgets/UserTypeImpl';
 import * as gristTypes from 'app/common/gristTypes';
 import { getReferencedTableId, isFullReferencingType } from 'app/common/gristTypes';
+import { WidgetType } from 'app/common/widgetTypes';
 import { CellValue } from 'app/plugin/GristData';
 import { bundleChanges, Computed, Disposable, fromKo,
          dom as grainjsDom, makeTestId, MultiHolder, Observable, styled, toKo } from 'grainjs';
@@ -129,9 +130,15 @@ export class FieldBuilder extends Disposable {
 
     // Observable with a list of available types.
     this._availableTypes = Computed.create(this, (use) => {
+      const isForm = use(use(this.field.viewSection).widgetType) === WidgetType.Form;
       const isFormula = use(this.origColumn.isFormula);
       const types: Array<IOptionFull<string>> = [];
       _.each(UserType.typeDefs, (def: any, key: string|number) => {
+        if (isForm && key === 'Attachments') {
+          // Attachments in forms are currently unsupported.
+          return;
+        }
+
         const o: IOptionFull<string> = {
           value: key as string,
           label: def.label,

app/client/widgets/TZAutocomplete.ts

@@ -52,7 +52,10 @@ export function buildTZAutocomplete(
 ) {
   // Set a large maxResults, since it's sometimes nice to see all supported timezones (there are
   // fewer than 1000 in practice).
-  const acIndex = new ACIndexImpl<ACSelectItem>(timezoneOptions(moment), 1000, true);
+  const acIndex = new ACIndexImpl<ACSelectItem>(timezoneOptions(moment), {
+    maxResults: 1000,
+    keepOrder: true,
+  });
 
   // Only save valid time zones. If there is no selected item, we'll auto-select and save only
   // when there is a good match.