feat(core): support ai network search (#9357)

### What Changed?
- Add `PerplexityProvider` in backend.
- Update session prompt name if user toggle network search mode in chat panel.
- Add experimental flag for AI network search feature.
- Add unit tests and e2e tests.

Search results are streamed and appear word for word:

<div class='graphite__hidden'>
          <div>🎥 Video uploaded on Graphite:</div>
            <a href="https://app.graphite.dev/media/video/sJGviKxfE3Ap685cl5bj/56f6ec7b-4b21-405f-9612-43e083f6fb84.mov">
              <img src="https://app.graphite.dev/api/v1/graphite/video/thumbnail/sJGviKxfE3Ap685cl5bj/56f6ec7b-4b21-405f-9612-43e083f6fb84.mov">
            </a>
          </div>
<video src="https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/sJGviKxfE3Ap685cl5bj/56f6ec7b-4b21-405f-9612-43e083f6fb84.mov">录屏2024-12-27 18.58.40.mov</video>

Click the little globe icon to manually turn on/off Internet search:
<div class='graphite__hidden'>
          <div>🎥 Video uploaded on Graphite:</div>
            <a href="https://app.graphite.dev/media/video/sJGviKxfE3Ap685cl5bj/778f1406-bf29-498e-a90d-7dad813392d1.mov">
              <img src="https://app.graphite.dev/api/v1/graphite/video/thumbnail/sJGviKxfE3Ap685cl5bj/778f1406-bf29-498e-a90d-7dad813392d1.mov">
            </a>
          </div>
<video src="https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/sJGviKxfE3Ap685cl5bj/778f1406-bf29-498e-a90d-7dad813392d1.mov">录屏2024-12-27 19.01.16.mov</video>

When there is an image, it will automatically switch to the openai model:

<div class='graphite__hidden'>
          <div>🎥 Video uploaded on Graphite:</div>
            <a href="https://app.graphite.dev/media/video/sJGviKxfE3Ap685cl5bj/56431d8e-75e1-4d84-ab4a-b6636042cc6a.mov">
              <img src="https://app.graphite.dev/api/v1/graphite/video/thumbnail/sJGviKxfE3Ap685cl5bj/56431d8e-75e1-4d84-ab4a-b6636042cc6a.mov">
            </a>
          </div>
<video src="https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/sJGviKxfE3Ap685cl5bj/56431d8e-75e1-4d84-ab4a-b6636042cc6a.mov">录屏2024-12-27 19.02.13.mov</video>

packages/frontend/graphql/src/graphql/index.ts

@@ -206,6 +206,17 @@ mutation createCopilotSession($options: CreateChatSessionInput!) {
 }`,
 };
 
+export const updateCopilotSessionMutation = {
+  id: 'updateCopilotSessionMutation' as const,
+  operationName: 'updateCopilotSession',
+  definitionName: 'updateCopilotSession',
+  containsFile: false,
+  query: `
+mutation updateCopilotSession($options: UpdateChatSessionInput!) {
+  updateCopilotSession(options: $options)
+}`,
+};
+
 export const createCustomerPortalMutation = {
   id: 'createCustomerPortalMutation' as const,
   operationName: 'createCustomerPortal',

packages/frontend/graphql/src/graphql/update-copilot-session.gql

@@ -0,0 +1,3 @@
+mutation updateCopilotSession($options: UpdateChatSessionInput!) {
+  updateCopilotSession(options: $options)
+}

packages/frontend/graphql/src/schema.ts

@@ -188,6 +188,11 @@ export interface CreateChatSessionInput {
   workspaceId: Scalars['String']['input'];
 }
 
+export interface UpdateChatSessionInput {
+  sessionId: Scalars['String']['input'];
+  promptName: Scalars['String']['input'];
+}
+
 export interface CreateCheckoutSessionInput {
   args?: InputMaybe<Scalars['JSONObject']['input']>;
   coupon?: InputMaybe<Scalars['String']['input']>;
@@ -688,6 +693,10 @@ export interface MutationCreateCopilotSessionArgs {
   options: CreateChatSessionInput;
 }
 
+export interface MutationUpdateCopilotSessionArgs {
+  options: UpdateChatSessionInput;
+}
+
 export interface MutationCreateInviteLinkArgs {
   expireTime: WorkspaceInviteLinkExpireTime;
   workspaceId: Scalars['String']['input'];
@@ -1596,6 +1605,15 @@ export type CreateCopilotSessionMutation = {
   createCopilotSession: string;
 };
 
+export type UpdateCopilotSessionMutationVariables = Exact<{
+  options: UpdateChatSessionInput;
+}>;
+
+export type UpdateCopilotSessionMutation = {
+  __typename?: 'Mutation';
+  updateCopilotSession: string;
+};
+
 export type CreateCustomerPortalMutationVariables = Exact<{
   [key: string]: never;
 }>;
@@ -3070,6 +3088,11 @@ export type Mutations =
       variables: CreateCopilotSessionMutationVariables;
       response: CreateCopilotSessionMutation;
     }
+  | {
+    name: 'updateCopilotSessionMutation';
+    variables: UpdateCopilotSessionMutationVariables;
+    response: UpdateCopilotSessionMutation;
+  }
   | {
       name: 'createCustomerPortalMutation';
       variables: CreateCustomerPortalMutationVariables;