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

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

+package theodolite.patcher
+
+import io.fabric8.kubernetes.api.model.KubernetesResource
+import io.fabric8.kubernetes.api.model.apps.Deployment
+
+/**
+ * The DataVolumeLoadGeneratorReplicaPatcher allows to modify the value of an environment variable
+ *
+ * @property k8sResource Kubernetes resource to be patched.
+ * @property container Container to be patched.
+ * @property variableName Name of the environment variable to be patched.
+ */
+class DataVolumeLoadGeneratorReplicaPatcher(
+    private val k8sResource: KubernetesResource,
+    private val maxVolume: String,
+    container: String,
+    variableName: String
+) : EnvVarPatcher(k8sResource, container, variableName) {
+
+    override fun <String> patch(value: String) {
+        if (k8sResource is Deployment) {
+            if (value is kotlin.String) {
+                val load = value.toInt()
+                val loadGenInstances = (load + maxVolume.toInt() - 1) / maxVolume.toInt()
+                this.k8sResource.spec.replicas = loadGenInstances
+                val loadPerInstance = load / loadGenInstances
+                super.patch(loadPerInstance.toString())
+            }
+        }
+    }
+}

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

@@ -12,7 +12,7 @@ import io.fabric8.kubernetes.api.model.apps.Deployment
  * @property container Container to be patched.
  * @property variableName Name of the environment variable to be patched.
  */
-class EnvVarPatcher(
+open class EnvVarPatcher(
     private val k8sResource: KubernetesResource,
     private val container: String,
     private val variableName: String

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

@@ -48,6 +48,12 @@ class PatcherFactory {
                     k8sResource = resource,
                     loadGenMaxRecords = patcherDefinition.properties["loadGenMaxRecords"]!!
                 )
+                "DataVolumeLoadGeneratorReplicaPatcher" -> DataVolumeLoadGeneratorReplicaPatcher(
+                    k8sResource = resource,
+                    maxVolume = patcherDefinition.properties["maxVolume"]!!,
+                    container = patcherDefinition.properties["container"]!!,
+                    variableName = patcherDefinition.properties["variableName"]!!
+                )
                 "EnvVarPatcher" -> EnvVarPatcher(
                     k8sResource = resource,
                     container = patcherDefinition.properties["container"]!!,