feat(runner-config): 🔥 add validation

Co-authored-by: Aksel Skaar Leirvaag <52233080+akselleirv@users.noreply.github.com>

api/v1alpha2/reference_types.go

@@ -163,10 +163,10 @@ type RunnerPodSpec struct {
 	// +optional
 	Image string `json:"image,omitempty"`
 
-	// Runner pod ImagePullPolicy to use other than default
+	// Runner pod ImagePullPolicy to use. Default is IfNotPresent.
 	// +optional
+        // +kubebuilder:validation:Enum=Always;IfNotPresent;Never
 	ImagePullPolicy string `json:"imagePullPolicy,omitempty"`
-
 	// List of sources to populate environment variables in the container.
 	// The keys defined within a source must be a C_IDENTIFIER. All invalid keys
 	// will be reported as an event when the container is starting. When a key exists in multiple