Fix proxy server for CurrentWorkspaceId method (#3703)

## Changes
This PR modifies the proxy server to use the new API client from the Go
SDK and then pass through the `X-Databricks-Org-Id`

## Why
To make the `w.CurrentWorkspaceId()` SDK call work, which relies on this
header.

## Tests
Existing tests pass. `bundle summary` which failed before with
`RecordRequests = true` passes now.

Author: shreyas-goenka

libs/testproxy/server.go

@@ -11,8 +11,8 @@ import (
 	"github.com/databricks/cli/internal/testutil"
 	"github.com/databricks/cli/libs/testserver"
 	"github.com/databricks/databricks-sdk-go/apierr"
-	"github.com/databricks/databricks-sdk-go/client"
 	"github.com/databricks/databricks-sdk-go/config"
+	"github.com/databricks/databricks-sdk-go/httpclient"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -22,7 +22,7 @@ type ProxyServer struct {
 
 	t testutil.TestingT
 
-	apiClient        *client.DatabricksClient
+	apiClient        *httpclient.ApiClient
 	RequestCallback  func(request *testserver.Request)
 	ResponseCallback func(request *testserver.Request, response *testserver.EncodedResponse)
 }
@@ -47,8 +47,10 @@ func New(t testutil.TestingT) *ProxyServer {
 	// In CI test environments this would read the appropriate environment
 	// variables.
 	var err error
-	s.apiClient, err = client.New(&config.Config{})
+	cfg := &config.Config{}
+	clientCfg, err := config.HTTPClientConfigFromConfig(cfg)
 	require.NoError(t, err)
+	s.apiClient = httpclient.NewApiClient(clientCfg)
 
 	// Set up the proxy handler as the default handler for all requests.
 	server := httptest.NewServer(http.HandlerFunc(s.proxyToCloud))
@@ -102,7 +104,29 @@ func (s *ProxyServer) proxyToCloud(w http.ResponseWriter, r *http.Request) {
 
 	reqBody := s.reqBody(request)
 	respBody := bytes.Buffer{}
-	err := s.apiClient.Do(context.Background(), r.Method, r.URL.Path, headers, queryParams, reqBody, &respBody)
+
+	// List of response headers to pass through to the client.
+	// We can extend this code to pass all X-Databricks headers if we introduce a
+	// more powerful visitor like `WithRequestHeaders` to the SDK. That is left
+	// as a future exercise for now.
+	includeResponseHeaders := []string{"X-Databricks-Org-Id"}
+	responseHeaders := make(map[string]*string)
+
+	visitors := []httpclient.DoOption{
+		httpclient.WithRequestHeaders(headers),
+		httpclient.WithQueryParameters(queryParams),
+		httpclient.WithRequestData(reqBody),
+		httpclient.WithResponseUnmarshal(&respBody),
+	}
+
+	for _, header := range includeResponseHeaders {
+		responseHeaders[header] = new(string)
+		visitors = append(visitors, httpclient.WithResponseHeader(header, responseHeaders[header]))
+	}
+
+	err := s.apiClient.Do(context.Background(), r.Method, r.URL.Path,
+		visitors...,
+	)
 
 	var encodedResponse *testserver.EncodedResponse
 
@@ -142,6 +166,12 @@ func (s *ProxyServer) proxyToCloud(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Send response to client.
+	if len(responseHeaders) > 0 {
+		for k, v := range responseHeaders {
+			w.Header()[k] = []string{*v}
+		}
+	}
+
 	w.WriteHeader(encodedResponse.StatusCode)
 
 	_, err = w.Write(encodedResponse.Body)