Refactor to remove redundant initialization and add NVS storage tests

- Removed unnecessary calls to relay_chn_create and g_is_component_initialized in multiple test cases across test_relay_chn_core_single.c, test_relay_chn_listener_multi.c, and test_relay_chn_listener_single.c.
- Introduced new test files for NVS functionality: test_relay_chn_nvs_multi.c and test_relay_chn_nvs_single.c, covering initialization, direction setting, invalid parameters, and erase operations.
- Updated partition table configuration to support NVS storage, including the addition of a new partition file part_nvs.csv.
- Adjusted sdkconfig files to enable NVS support and configure custom partition settings for relay channels.

test_apps/sdkconfig

@@ -395,13 +395,13 @@ CONFIG_ESPTOOLPY_MONITOR_BAUD=115200
 #
 # Partition Table
 #
-CONFIG_PARTITION_TABLE_SINGLE_APP=y
+# CONFIG_PARTITION_TABLE_SINGLE_APP is not set
 # CONFIG_PARTITION_TABLE_SINGLE_APP_LARGE is not set
 # CONFIG_PARTITION_TABLE_TWO_OTA is not set
 # CONFIG_PARTITION_TABLE_TWO_OTA_LARGE is not set
-# CONFIG_PARTITION_TABLE_CUSTOM is not set
-CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions.csv"
-CONFIG_PARTITION_TABLE_FILENAME="partitions_singleapp.csv"
+CONFIG_PARTITION_TABLE_CUSTOM=y
+CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions/part_nvs.csv"
+CONFIG_PARTITION_TABLE_FILENAME="partitions/part_nvs.csv"
 CONFIG_PARTITION_TABLE_OFFSET=0x8000
 CONFIG_PARTITION_TABLE_MD5=y
 # end of Partition Table
@@ -1162,6 +1162,13 @@ CONFIG_NEWLIB_TIME_SYSCALL_USE_RTC_HRT=y
 # CONFIG_NEWLIB_TIME_SYSCALL_USE_NONE is not set
 # end of Newlib
 
+#
+# NVS
+#
+# CONFIG_NVS_ASSERT_ERROR_CHECK is not set
+# CONFIG_NVS_LEGACY_DUP_KEYS_COMPATIBILITY is not set
+# end of NVS
+
 #
 # PThreads
 #
@@ -1263,7 +1270,16 @@ CONFIG_UNITY_ENABLE_IDF_TEST_RUNNER=y
 CONFIG_RELAY_CHN_OPPOSITE_INERTIA_MS=200
 CONFIG_RELAY_CHN_COUNT=1
 CONFIG_RELAY_CHN_ENABLE_TILTING=y
+CONFIG_RELAY_CHN_ENABLE_NVS=y
 # end of Relay Channel Driver Configuration
+
+#
+# Relay Channel NVS Storage Configuration
+#
+CONFIG_RELAY_CHN_NVS_NAMESPACE="relay_chn"
+CONFIG_RELAY_CHN_NVS_CUSTOM_PARTITION=y
+CONFIG_RELAY_CHN_NVS_CUSTOM_PARTITION_NAME="app_data"
+# end of Relay Channel NVS Storage Configuration
 # end of Component config
 
 # CONFIG_IDF_EXPERIMENTAL_FEATURES is not set