Introduce SparkCluster CRD to Deploy Spark Standalone Clusters on Kubernetes

### What feature you would like to be added?

Add a new CustomResourceDefinition (CRD) called `SparkCluster` to enable declarative lifecycle management of Spark Standalone clusters on Kubernetes.

### Why is this needed?

Currently, the Spark Operator supports only cluster-mode Spark applications via the `ScheduledSparkApplication` and `SparkApplication` CRDs. However, there is no native way to deploy and manage a long-running Spark Standalone cluster (with dedicated Master and Worker nodes) on Kubernetes using the operator.

### Describe the solution you would like

Add a new CRD called `SparkCluster` and implement the corressponding controller logic. An example manifest can be something like:

```yaml
apiVersion: sparkoperator.k8s.io/v1alpha1
kind: SparkCluster
metadata:
name: spark
namespace: default
spec:
sparkVersion: 4.0.1
sparkConf:
spark.master.ui.port: "8080"
spark.master.ui.title: "Example Spark Cluster"
master:
template:
metadata:
labels:
spark.apache.org/version: 4.0.1
annotations:
spark.apache.org/version: 4.0.1
spec:
containers:
- name: spark-master
image: docker.io/library/spark:4.0.1
imagePullPolicy: Always
resources:
requests:
cpu: 1
memory: 4Gi
limits:
cpu: 1
memory: 4Gi
securityContext:
allowPrivilegeEscalation: false
capabilities:
drop:
- ALL
runAsNonRoot: true
runAsUser: 185
runAsGroup: 185
fsGroup: 185
seccompProfile:
type: RuntimeDefault
workerGroups:
- name: group0
replicas: 2
template:
metadata:
labels:
spark.apache.org/version: 4.0.1
annotations:
spark.apache.org/version: 4.0.1
containers:
- name: spark-master
image: docker.io/library/spark:4.0.1
imagePullPolicy: Always
resources:
requests:
cpu: 1
memory: 4Gi
limits:
cpu: 1
memory: 4Gi
securityContext:
allowPrivilegeEscalation: false
capabilities:
drop:
- ALL
runAsNonRoot: true
runAsUser: 185
runAsGroup: 185
fsGroup: 185
seccompProfile:
type: RuntimeDefault
- name: group1
replicas: 1
template:
metadata:
labels:
spark.apache.org/version: 4.0.1
annotations:
spark.apache.org/version: 4.0.1
containers:
- name: spark-master
image: docker.io/library/spark:4.0.1
imagePullPolicy: Always
resources:
requests:
cpu: 2
memory: 8Gi
limits:
cpu: 2
memory: 8Gi
securityContext:
allowPrivilegeEscalation: false
capabilities:
drop:
- ALL
runAsNonRoot: true
runAsUser: 185
runAsGroup: 185
fsGroup: 185
seccompProfile:
type: RuntimeDefault

```

### Describe alternatives you have considered

_No response_

### Additional context

[apache/spark-kubernetes-operator](https://github.com/apache/spark-kubernetes-operator) supports `SparkCluster` CRD.

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