feat(github_graphql): introduce graphql client with shared auth and integrate into task flow

- added CreateGraphqlClient to encapsulate graphql client construction
- reused CreateAuthenticatedHttpClient from github/tasks to inject token refresh via RoundTripper
- replaced manual graphql client setup in PrepareTaskData with new factory function
- preserved existing rate limit handling via getRateRemaining callback
- preserved query cost calculation using SetGetRateCost

Technical details:
- graphql client now uses http transport with TokenProvider and RefreshRoundTripper
- removes dependency on oauth2 client and avoids token expiration issues
- decouples graphql client from REST ApiClient by avoiding reuse of apiClient.GetClient()
- maintains compatibility with github.com and enterprise graphql endpoints

Note:
- shared auth logic remains in github/tasks and is imported with alias to avoid package name collision
- introduces cross-plugin dependency (github_graphql → github/tasks) as a pragmatic tradeoff to avoid duplication

Author: Ke-vin-S

backend/plugins/github_graphql/impl/impl.go

@@ -20,7 +20,6 @@ package impl
 import (
 	"context"
 	"fmt"
-	"net/url"
 	"reflect"
 	"time"
 
@@ -177,19 +176,9 @@ func (p GithubGraphql) PrepareTaskData(taskCtx plugin.TaskContext, options map[s
 		return nil, err
 	}
 
-	endpoint, err := errors.Convert01(url.Parse(connection.Endpoint))
-	if err != nil {
-		return nil, errors.BadInput.Wrap(err, fmt.Sprintf("malformed connection endpoint supplied: %s", connection.Endpoint))
-	}
-	// github.com and github enterprise have different graphql endpoints
-	endpoint.Path = "/graphql" // see https://docs.github.com/en/graphql/guides/forming-calls-with-graphql
-	if endpoint.Hostname() != "api.github.com" {
-		// see https://docs.github.com/en/enterprise-server@3.11/graphql/guides/forming-calls-with-graphql
-		endpoint.Path = "/api/graphql"
-	}
-
-	client := graphql.NewClient(endpoint.String(), apiClient.GetClient())
-	graphqlClient, err := helper.CreateAsyncGraphqlClient(taskCtx, client, taskCtx.GetLogger(),
+	graphqlClient, err := tasks.CreateGraphqlClient(
+		taskCtx,
+		connection,
 		func(ctx context.Context, client *graphql.Client, logger log.Logger) (rateRemaining int, resetAt *time.Time, err errors.Error) {
 			var query GraphQueryRateLimit
 			dataErrors, err := errors.Convert01(client.Query(taskCtx.GetContext(), &query, nil))

backend/plugins/github_graphql/tasks/graphql_client.go

@@ -0,0 +1,69 @@
+/*
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements.  See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to You under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License.  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package tasks
+
+import (
+	"context"
+	"fmt"
+	"github.com/apache/incubator-devlake/core/log"
+	"net/url"
+	"time"
+
+	"github.com/apache/incubator-devlake/core/errors"
+	"github.com/apache/incubator-devlake/core/plugin"
+	helper "github.com/apache/incubator-devlake/helpers/pluginhelper/api"
+	"github.com/apache/incubator-devlake/plugins/github/models"
+	githubTasks "github.com/apache/incubator-devlake/plugins/github/tasks"
+	"github.com/merico-ai/graphql"
+)
+
+func CreateGraphqlClient(
+	taskCtx plugin.TaskContext,
+	connection *models.GithubConnection,
+	getRateRemaining func(context.Context, *graphql.Client, log.Logger) (rateRemaining int, resetAt *time.Time, err errors.Error),
+) (*helper.GraphqlAsyncClient, errors.Error) {
+
+	// inject the shared auth layer
+	httpClient, err := githubTasks.CreateAuthenticatedHttpClient(taskCtx, connection, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Build endpoint
+	endpoint, err := errors.Convert01(url.Parse(connection.Endpoint))
+	if err != nil {
+		return nil, errors.BadInput.Wrap(err, fmt.Sprintf("malformed connection endpoint supplied: %s", connection.Endpoint))
+	}
+	// github.com and github enterprise have different graphql endpoints
+	if endpoint.Hostname() == "api.github.com" {
+		// see https://docs.github.com/en/graphql/guides/forming-calls-with-graphql
+		endpoint.Path = "/graphql"
+	} else {
+		// see https://docs.github.com/en/enterprise-server@3.11/graphql/guides/forming-calls-with-graphql
+		endpoint.Path = "/api/graphql"
+	}
+
+	gqlClient := graphql.NewClient(endpoint.String(), httpClient)
+
+	return helper.CreateAsyncGraphqlClient(
+		taskCtx,
+		gqlClient,
+		taskCtx.GetLogger(),
+		getRateRemaining,
+	)
+}