(core) Fixing couple of bugs in collapsed section layout

Summary:
The previous implementation for collapsing sections involved disposing of a view instance (Grid or Chart component). This caused numerous bugs with
linking sections as the implementation is located in the BaseView.js. Now the view instance is kept and attached to a dom in a hidden div, so it can respond
and function as a normal rendered section. It is also passed from between collapsed and main layout, when sections are dragged or moved using section's
menu commands (`collapse` and `add to main page`)

It also implies that the ViewLayout must still be rendered when a section is maximized (as it is responsible for the view instance), so the dom, and
some logic for rendering it, had to be changed.

Test Plan: New and updated

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3826

app/client/components/buildViewSectionDom.ts

@@ -29,13 +29,13 @@ export function buildCollapsedSectionDom(options: {
   const vs: ViewSectionRec = gristDoc.docModel.viewSections.getRowModel(sectionRowId);
   const typeComputed = Computed.create(null, use => getWidgetTypes(use(vs.parentKey) as any).icon);
   return cssMiniSection(
-    testId(`minilayout-section-${sectionRowId}`),
-    testId(`minilayout-section`),
+    testId(`collapsed-section-${sectionRowId}`),
+    testId(`collapsed-section`),
     cssDragHandle(
       dom.domComputed(typeComputed, (type) => icon(type)),
       dom('div', {style: 'margin-right: 16px;'}),
       dom.maybe((use) => use(use(vs.table).summarySourceTable), () => cssSigmaIcon('Pivot', testId('sigma'))),
-      dom('span.viewsection_title_font', testId('viewsection-title'),
+      dom('span.viewsection_title_font', testId('collapsed-section-title'),
         dom.text(vs.titleDef),
       ),
     ),
@@ -102,7 +102,7 @@ export function buildViewSectionDom(options: {
           dom('div.viewsection_truncated', 'Not all data is shown')
         ),
         dom.cls((use) => 'viewsection_type_' + use(vs.parentKey)),
-        viewInstance.viewPane,
+        viewInstance.viewPane
       ),
       dom.maybe(use => !use(isNarrowScreenObs()), () => viewInstance.selectionSummary?.buildDom()),
     ]),