(core) Adding colors to toast notification

Summary:
Styling toast notification. Adding colors and icons.
In Grist, changed the default style for errors (will be shown in red), and a style for
Linked copied to clipboard (will be shown in Green).
All other colors are not used currently, left for another diff.

Test Plan: manual

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3053

app/client/components/BaseView.js

@@ -17,7 +17,7 @@ var commands = require('./commands');
 var BackboneEvents = require('backbone').Events;
 const {LinkingState} = require('./LinkingState');
 const {ClientColumnGetters} = require('app/client/models/ClientColumnGetters');
-const {reportError, UserError} = require('app/client/models/errors');
+const {reportError, reportSuccess} = require('app/client/models/errors');
 const {urlState} = require('app/client/models/gristUrlState');
 const {SectionFilter} = require('app/client/models/SectionFilter');
 const {copyToClipboard} = require('app/client/lib/copyToClipboard');
@@ -318,7 +318,7 @@ BaseView.prototype.copyLink = async function() {
     const link = urlState().makeUrl({ hash: { sectionId, rowId, colRef } });
     await copyToClipboard(link);
     setTestState({clipboard: link});
-    reportError(new UserError('Link copied to clipboard', {key: 'clipboard'}));
+    reportSuccess('Link copied to clipboard', {key: 'clipboard'});
   } catch (e) {
     throw new Error('cannot copy to clipboard');
   }

app/client/components/Drafts.ts

@@ -270,7 +270,7 @@ class NotificationAdapter extends Disposable implements Notification {
   }
   public showUndoDiscard() {
     const notifier = this._doc.app.topAppModel.notifier;
-    const notification = notifier.createUserError("Undo discard", {
+    const notification = notifier.createUserMessage("Undo discard", {
       message: () =>
         discardNotification(
           dom.on("click", () => {