feat(server): add search docs by keyword gql api (#12866)

close AI-220









#### PR Dependency Tree


* **PR #12866** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Introduced a new document search capability, allowing users to search
for documents by keyword within a workspace.
- Search results include document details such as title, highlights,
creation and update timestamps, and creator/updater information.
  - Added support for limiting the number of search results returned.
- **Tests**
- Added comprehensive end-to-end and snapshot tests to ensure accuracy
and access control for the new search functionality.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/plugins/indexer/resolver.ts

@@ -10,6 +10,8 @@ import { IndexerService, SearchNodeWithMeta } from './service';
 import {
   AggregateInput,
   AggregateResultObjectType,
+  SearchDocObjectType,
+  SearchDocsInput,
   SearchInput,
   SearchQueryOccur,
   SearchQueryType,
@@ -86,6 +88,29 @@ export class IndexerResolver {
     };
   }
 
+  @ResolveField(() => [SearchDocObjectType], {
+    description: 'Search docs by keyword',
+  })
+  async searchDocs(
+    @CurrentUser() me: UserType,
+    @Parent() workspace: WorkspaceType,
+    @Args('input') input: SearchDocsInput
+  ): Promise<SearchDocObjectType[]> {
+    const docs = await this.indexer.searchDocsByKeyword(
+      workspace.id,
+      input.keyword,
+      {
+        limit: input.limit,
+      }
+    );
+
+    const needs = await this.ac
+      .user(me.id)
+      .workspace(workspace.id)
+      .docs(docs, 'Doc.Read');
+    return needs;
+  }
+
   #addWorkspaceFilter(
     workspace: WorkspaceType,
     input: SearchInput | AggregateInput