(core) Expanding widgets

Summary:
New icon to expand an active section and show it as a popup (just like raw data views).

"Show raw data" popup couldn't be reused (as it is basically a different page), so now
we have two kinds of popups that look the same.

1. Raw data popup - to show an alien section on a page (a section from a different view). This is used by "Show raw data" button, it is basically a different page that shows an arbitrary section.

2. Layout popup - a popup generated by Layout.ts that basically hides every other section and adds an overlay effect to itself.

Other changes
- Layout.js was migrated to typescript
- "Show raw data" menu item was converted to link

Test Plan: new tests

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3764

test/nbrowser/gristUtils.ts

@@ -238,6 +238,19 @@ export async function selectSectionByTitle(title: string) {
   }
 }
 
+export async function expandSection(title?: string) {
+  const select = title
+    ? driver.findContent(`.test-viewsection-title`, exactMatch(title)).findClosest(".viewsection_title")
+    : driver.find(".active_section");
+  await select.find(".test-section-menu-expandSection").click();
+}
+
+export async function getSectionId() {
+  const classList = await driver.find(".active_section").getAttribute("class");
+  const match = classList.match(/test-viewlayout-section-(\d+)/);
+  if (!match) { throw new Error("Could not find section id"); }
+  return parseInt(match[1]);
+}
 
 /**
  * Returns visible cells of the GridView from a single column and one or more rows. Options may be