Add a Patcher to handle ospbench data volume settings

This handler takes the total defined load and compute the needed load generator instances and set the volume that each generator should generate.

Needed for OSPBench

theodolite/src/main/kotlin/theodolite/patcher/DataVolumeLoadGeneratorReplicaPatcher.kt

+package theodolite.patcher
+
+import io.fabric8.kubernetes.api.model.KubernetesResource
+
+/**
+ * The DataVolumeLoadGeneratorReplicaPatcher takes the total load that should be generated
+ * and computes the number of instances needed for this load based on the `maxVolume`
+ * ((load + maxVolume - 1) / maxVolume) and calculates the load per instance
+ * (loadPerInstance = load / instances).
+ * The number of instances are set for the load generator and the given variable is set to the
+ * load per instance.
+ *
+ * @property k8sResource Kubernetes resource to be patched.
+ * @property maxVolume per load generator instance
+ * @property container Container to be patched.
+ * @property variableName Name of the environment variable to be patched.
+ */
+class DataVolumeLoadGeneratorReplicaPatcher(
+    k8sResource: KubernetesResource,
+    private val maxVolume: Int,
+    container: String,
+    variableName: String
+) : AbstractPatcher(k8sResource) {
+
+    private val replicaPatcher = ReplicaPatcher(k8sResource)
+    private val envVarPatcher = EnvVarPatcher(k8sResource, container, variableName)
+
+    override fun <T> patch(value: T) {
+        // calculate number of load generator instances and load per instance
+        val load = Integer.parseInt(value.toString())
+        val loadGenInstances = (load + maxVolume - 1) / maxVolume
+        val loadPerInstance = load / loadGenInstances
+
+        // Patch instance values and load value of generators
+        replicaPatcher.patch(loadGenInstances.toString())
+        envVarPatcher.patch(loadPerInstance.toString())
+    }
+}