feat: add include for nexus base package in nexus variant samples

nexuscancellation, nexuscontextpropagation, and nexusmultipleargs
import classes from the base nexus package. The include field tells
the CLI to extract the nexus package alongside the variant.

Author: dandavison

temporal-sample.yaml

@@ -43,6 +43,9 @@ samples:
     dest: src/main/java/io/temporal/samples/nexuscancellation
     description: Cancel a Nexus operation using WaitRequested cancellation
     sdk_version: "1.32.1"
+    include:
+      - path: core/src/main/java/io/temporal/samples/nexus
+        dest: src/main/java/io/temporal/samples/nexus
     commands:
       - cmd: "temporal operator namespace create --namespace my-target-namespace"
       - cmd: "temporal operator namespace create --namespace my-caller-namespace"
@@ -56,6 +59,9 @@ samples:
     dest: src/main/java/io/temporal/samples/nexuscontextpropagation
     description: Propagate MDC context from Workflows to Nexus operations
     sdk_version: "1.32.1"
+    include:
+      - path: core/src/main/java/io/temporal/samples/nexus
+        dest: src/main/java/io/temporal/samples/nexus
     commands:
       - cmd: "temporal operator namespace create --namespace my-target-namespace"
       - cmd: "temporal operator namespace create --namespace my-caller-namespace"
@@ -69,6 +75,9 @@ samples:
     dest: src/main/java/io/temporal/samples/nexusmultipleargs
     description: Map a Nexus operation to a workflow with multiple input arguments
     sdk_version: "1.32.1"
+    include:
+      - path: core/src/main/java/io/temporal/samples/nexus
+        dest: src/main/java/io/temporal/samples/nexus
     commands:
       - cmd: "temporal operator namespace create --namespace my-target-namespace"
       - cmd: "temporal operator namespace create --namespace my-caller-namespace"