Implement DefaultTechDocsCollator

* Implements a collator for tech docs.
   * Retrieves mkdocs created search index for entities that have documentation configured
* Registers collator to expose tech docs content to be searchable
* Adds pagination to example search
* Modifies example search to contain tech docs
   * Displays docs results with link to docs and the entity name as title.
* Creates a reusable type filter to be located in the search package.
* Add tests for type filter

Signed-off-by: Jussi Hallila <jussi@hallila.com>

packages/backend/src/plugins/search.ts

@@ -21,6 +21,7 @@ import {
 } from '@backstage/plugin-search-backend-node';
 import { PluginEnvironment } from '../types';
 import { DefaultCatalogCollator } from '@backstage/plugin-catalog-backend';
+import { DefaultTechDocsCollator } from '@backstage/plugin-techdocs-backend';
 
 export default async function createPlugin({
   logger,
@@ -37,6 +38,11 @@ export default async function createPlugin({
     collator: new DefaultCatalogCollator({ discovery }),
   });
 
+  indexBuilder.addCollator({
+    defaultRefreshIntervalSeconds: 600,
+    collator: new DefaultTechDocsCollator({ discovery, logger }),
+  });
+
   // The scheduler controls when documents are gathered from collators and sent
   // to the search engine for indexing.
   const { scheduler } = await indexBuilder.build();