Load datasets + Datasets grid + Datasets search (#889)

* [examples/openspending][m] - added loader + fetching from datapackage

- Also added an indexing example

* [examples/openspending,home][xl]: removes datasets table, implement dataset cards grid, implement country facet

* [examples/openspending,home][m]: add min date and max date facets

---------

Co-authored-by: Luccas Mateus de Medeiros Gomes <luccasmmg@gmail.com>

examples/openspending/lib/project.interface.ts

@@ -0,0 +1,21 @@
+import {
+  FiscalDataPackage,
+  TabularDataResource,
+} from './datapackage.interface';
+
+export interface Project {
+  owner: { name: string; logo?: string; title?: string }; // Info about the owner of the data repo
+  repo: { name: string; full_name: string }; // Info about the the data repo
+  files: TabularDataResource[];
+  name: string;
+  title?: string;
+  author?: string;
+  cityCode?: string;
+  countryCode?: string;
+  fiscalPeriod?: {
+    start: string;
+    end: string;
+  };
+  readme?: string;
+  datapackage: FiscalDataPackage;
+}