feat(server): add cloud indexer with Elasticsearch and Manticoresearch providers (#11835)

close CLOUD-137

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

- **New Features**
  - Introduced advanced workspace-scoped search and aggregation capabilities with support for complex queries, highlights, and pagination.
  - Added pluggable search providers: Elasticsearch and Manticoresearch.
  - New GraphQL queries, schema types, and resolver support for search and aggregation.
  - Enhanced configuration options for search providers in self-hosted and cloud deployments.
  - Added Docker Compose services and environment variables for Elasticsearch and Manticoresearch.
  - Integrated indexer service into deployment and CI workflows.

- **Bug Fixes**
  - Improved error handling with new user-friendly error messages for search provider and indexer issues.

- **Documentation**
  - Updated configuration examples and environment variable references for indexer and search providers.

- **Tests**
  - Added extensive end-to-end and provider-specific tests covering indexing, searching, aggregation, deletion, and error cases.
  - Included snapshot tests and test fixtures for search providers.

- **Chores**
  - Updated deployment scripts, Helm charts, and Kubernetes manifests to include indexer-related environment variables and secrets.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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

@@ -0,0 +1,61 @@
+import { z } from 'zod';
+
+import { defineModuleConfig } from '../../base';
+
+export enum SearchProviderType {
+  Manticoresearch = 'manticoresearch',
+  Elasticsearch = 'elasticsearch',
+}
+
+const SearchProviderTypeSchema = z.nativeEnum(SearchProviderType);
+
+declare global {
+  interface AppConfigSchema {
+    indexer: {
+      enabled: boolean;
+      provider: {
+        type: SearchProviderType;
+        endpoint: string;
+        username: string;
+        password: string;
+      };
+    };
+  }
+}
+
+defineModuleConfig('indexer', {
+  enabled: {
+    desc: 'Enable indexer plugin',
+    default: true,
+  },
+  'provider.type': {
+    desc: 'Indexer search service provider name',
+    default: SearchProviderType.Manticoresearch,
+    shape: SearchProviderTypeSchema,
+    env: ['AFFINE_INDEXER_SEARCH_PROVIDER', 'string'],
+  },
+  'provider.endpoint': {
+    desc: 'Indexer search service endpoint',
+    default: 'http://localhost:9308',
+    env: ['AFFINE_INDEXER_SEARCH_ENDPOINT', 'string'],
+    validate: val => {
+      // allow to be nullable and empty string
+      if (!val) {
+        return { success: true, data: val };
+      }
+
+      return z.string().url().safeParse(val);
+    },
+  },
+  'provider.username': {
+    desc: 'Indexer search service auth username, if not set, basic auth will be disabled. Optional for elasticsearch',
+    link: 'https://www.elastic.co/guide/en/elasticsearch/reference/current/http-clients.html',
+    default: '',
+    env: ['AFFINE_INDEXER_SEARCH_USERNAME', 'string'],
+  },
+  'provider.password': {
+    desc: 'Indexer search service auth password, if not set, basic auth will be disabled. Optional for elasticsearch',
+    default: '',
+    env: ['AFFINE_INDEXER_SEARCH_PASSWORD', 'string'],
+  },
+});