[SPARK-53992] Add SparkOperatorConfManager.getAll method

### What changes were proposed in this pull request?

This PR aims to add `SparkOperatorConfManager.getAll` method to get all configurations.

### Why are the changes needed?

Like Apache Spark `SparkConf.getAll` API, we had better support `getAll` API.

https://github.com/apache/spark/blob/0be5f96e7a7d1b9fb9f96f1914019f79ef973a25/core/src/main/scala/org/apache/spark/SparkConf.scala#L197

```scala
/** Get all parameters as a list of pairs */
def getAll: Array[(String, String)]
```

### Does this PR introduce _any_ user-facing change?

No because this is a new API.

### How was this patch tested?

Pass the CIs with newly added test case.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #402 from dongjoon-hyun/SPARK-53992.

Authored-by: Dongjoon Hyun <[email protected]>
Signed-off-by: Dongjoon Hyun <[email protected]>

Author: dongjoon-hyun

spark-operator/src/main/java/org/apache/spark/k8s/operator/config/SparkOperatorConfManager.java

@@ -60,6 +60,21 @@ protected SparkOperatorConfManager() {
     initialize();
   }
 
+  /**
+   * Returns all properties.
+   *
+   * @return a Properties instance contains all properties.
+   */
+  public Properties getAll() {
+    synchronized (this) {
+      Properties properties = new Properties();
+      properties.putAll(initialConfig);
+      properties.putAll(metricsConfig);
+      properties.putAll(configOverrides);
+      return properties;
+    }
+  }
+
   /**
    * Returns the current value for a given configuration key, considering dynamic overrides.
    *

spark-operator/src/test/java/org/apache/spark/k8s/operator/config/SparkOperatorConfManagerTest.java

@@ -74,4 +74,41 @@ void testOverrideProperties() {
       }
     }
   }
+
+  @Test
+  void testGetAll() {
+    String propBackUp = System.getProperty("spark.kubernetes.operator.foo");
+    System.setProperty("spark.kubernetes.operator.foo", "bar");
+    try {
+      SparkOperatorConfManager confManager = new SparkOperatorConfManager();
+
+      // Check initial configurations.
+      int initialSize = confManager.getAll().size();
+      Assertions.assertEquals(initialSize, confManager.initialConfig.size());
+      Assertions.assertEquals(0, confManager.configOverrides.size());
+      Assertions.assertEquals(0, confManager.metricsConfig.size());
+      Assertions.assertEquals(initialSize, confManager.getAll().size());
+
+      // Override existing config
+      confManager.refresh(Map.of("spark.kubernetes.operator.foo", "barbar"));
+      Assertions.assertEquals(initialSize, confManager.initialConfig.size());
+      Assertions.assertEquals(1, confManager.configOverrides.size());
+      Assertions.assertEquals(0, confManager.metricsConfig.size());
+      Assertions.assertEquals(initialSize, confManager.getAll().size());
+
+      // Override new configs and metrics
+      confManager.refresh(Map.of("k1", "v1", "k2", "v2"));
+      confManager.metricsConfig.put("m", "v");
+      Assertions.assertEquals(initialSize, confManager.initialConfig.size());
+      Assertions.assertEquals(2, confManager.configOverrides.size());
+      Assertions.assertEquals(1, confManager.metricsConfig.size());
+      Assertions.assertEquals(initialSize + 3, confManager.getAll().size());
+    } finally {
+      if (StringUtils.isNotEmpty(propBackUp)) {
+        System.setProperty("spark.kubernetes.operator.foo", propBackUp);
+      } else {
+        System.clearProperty("spark.kubernetes.operator.foo");
+      }
+    }
+  }
 }