(core) Initial data tables page

Summary:
- Added a new special page for viewing raw data widgets:
  - Implemented in DataTables.ts
  - Accessible only via the special URL path `/p/data`
  - Future diffs should make this page prettier and easily accessible
  - Shows a list of user tables
  - Clicking on a table name shows its `rawViewSection` by setting `GristDoc.viewModel.activeSectionId`. Note that in this case `GristDoc.viewModel` is an empty record, so this is a bit of a hack, but it works well and causes no known issues.
- Added `ViewSectionRec.isRaw` to know if the record represents a raw data widget.
- Added various restrictions in the UI for raw data widgets:
  - 'Delete widget' is disabled in the 3-dot widget menu.
  - Prevent hiding columns:
    - "Hide column" in the column context menu is disabled
    - The "VISIBLE/HIDDEN COLUMNS" section of the right panel > Table > Widget is hidden
  - The toggle bar isn't configurable to ensure that users know when raw data is filtered:
    - The filter bar always shows if and only if some filters are present
    - "Toggle Filter Bar" is hidden in:
      - Right panel > Table > Sort & Filter
      - The sort/filter menu next to the three-dot menu for widgets.
  - Other restrictions in the right panel:
    - In the Column tab:
      - 'Use separate settings' is disabled
    - In the Table tab:
      - In the Widget subtab:
        - 'Change Widget' is hidden
      - In the Data subtab:
        - 'Edit Data Selection' is hidden
        - 'SELECT BY' is hidden

Test Plan: Tested manually. The behaviour of raw data widgets may still change and they aren't easily visible to users yet.

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3248

app/client/models/entities/TableRec.ts

@@ -1,5 +1,5 @@
 import {KoArray} from 'app/client/lib/koArray';
-import {DocModel, IRowModel, recordSet, refRecord} from 'app/client/models/DocModel';
+import {DocModel, IRowModel, recordSet, refRecord, ViewSectionRec} from 'app/client/models/DocModel';
 import {ColumnRec, ValidationRec, ViewRec} from 'app/client/models/DocModel';
 import {MANUALSORT} from 'app/common/gristTypes';
 import * as ko from 'knockout';
@@ -12,6 +12,7 @@ export interface TableRec extends IRowModel<"_grist_Tables"> {
   validations: ko.Computed<KoArray<ValidationRec>>;
 
   primaryView: ko.Computed<ViewRec>;
+  rawViewSection: ko.Computed<ViewSectionRec>;
   summarySource: ko.Computed<TableRec>;
 
   // A Set object of colRefs for all summarySourceCols of table.
@@ -37,6 +38,7 @@ export function createTableRec(this: TableRec, docModel: DocModel): void {
   this.validations = recordSet(this, docModel.validations, 'tableRef');
 
   this.primaryView = refRecord(docModel.views, this.primaryViewId);
+  this.rawViewSection = refRecord(docModel.viewSections, this.rawViewSectionRef);
   this.summarySource = refRecord(docModel.tables, this.summarySourceTable);
 
   // A Set object of colRefs for all summarySourceCols of this table.

app/client/models/entities/ViewRec.ts

@@ -32,7 +32,9 @@ export function createViewRec(this: ViewRec, docModel: DocModel): void {
     // The default function which is used when the conditional case is true.
     // Read may occur for recently disposed sections, must check condition first.
     return !this.isDisposed() &&
-      this.viewSections().all().length > 0 ? this.viewSections().at(0)!.getRowId() : 0;
+      // `!this.getRowId()` implies that this is an empty (non-existent) view record
+      // which happens when viewing the raw data tables, in which case the default is no active view section.
+      this.getRowId() && this.viewSections().all().length > 0 ? this.viewSections().at(0)!.getRowId() : 0;
   });
 
   this.activeSection = refRecord(docModel.viewSections, this.activeSectionId);

app/client/models/entities/ViewSectionRec.ts

@@ -47,6 +47,10 @@ export interface ViewSectionRec extends IRowModel<"_grist_Views_section"> {
   tableTitle: ko.Computed<string>;
   titleDef: modelUtil.KoSaveableObservable<string>;
 
+  // true if this record is its table's rawViewSection, i.e. a 'raw data view'
+  // in which case the UI prevents various things like hiding columns or changing the widget type.
+  isRaw: ko.Computed<boolean>;
+
   borderWidthPx: ko.Computed<string>;
 
   layoutSpecObj: modelUtil.ObjObservable<any>;
@@ -276,6 +280,10 @@ export function createViewSectionRec(this: ViewSectionRec, docModel: DocModel):
     )
   );
 
+  // true if this record is its table's rawViewSection, i.e. a 'raw data view'
+  // in which case the UI prevents various things like hiding columns or changing the widget type.
+  this.isRaw = this.autoDispose(ko.pureComputed(() => this.table().rawViewSectionRef() === this.getRowId()));
+
   this.borderWidthPx = ko.pureComputed(function() { return this.borderWidth() + 'px'; }, this);
 
   this.layoutSpecObj = modelUtil.jsonObservable(this.layoutSpec);