fix: Protect codersdk.Client SessionToken so it can be updated (#4965)

This feature is used by the coder agent to exchange a new token. By
protecting the SessionToken via mutex we ensure there are no data races
when accessing it.

enterprise/coderd/replicas_test.go

@@ -36,7 +36,7 @@ func TestReplicas(t *testing.T) {
 				Pubsub:   pubsub,
 			},
 		})
-		secondClient.SessionToken = firstClient.SessionToken
+		secondClient.SetSessionToken(firstClient.SessionToken())
 		ents, err := secondClient.Entitlements(context.Background())
 		require.NoError(t, err)
 		require.Len(t, ents.Errors, 1)
@@ -67,7 +67,7 @@ func TestReplicas(t *testing.T) {
 				Pubsub:   pubsub,
 			},
 		})
-		secondClient.SessionToken = firstClient.SessionToken
+		secondClient.SetSessionToken(firstClient.SessionToken())
 		replicas, err := secondClient.Replicas(context.Background())
 		require.NoError(t, err)
 		require.Len(t, replicas, 2)
@@ -110,7 +110,7 @@ func TestReplicas(t *testing.T) {
 				TLSCertificates: certificates,
 			},
 		})
-		secondClient.SessionToken = firstClient.SessionToken
+		secondClient.SetSessionToken(firstClient.SessionToken())
 		replicas, err := secondClient.Replicas(context.Background())
 		require.NoError(t, err)
 		require.Len(t, replicas, 2)

enterprise/coderd/workspaceagents_test.go

@@ -120,7 +120,7 @@ func setupWorkspaceAgent(t *testing.T, client *codersdk.Client, user codersdk.Cr
 			},
 		},
 	}
-	agentClient.SessionToken = authToken
+	agentClient.SetSessionToken(authToken)
 	agentCloser := agent.New(agent.Options{
 		Client: agentClient,
 		Logger: slogtest.Make(t, nil).Named("agent"),