samples: task_wdt: add scenario without hw fallback

Add new sample scenario without using a hardware watchdog as fallback.
This is used for the moment only for the mr_canhubk3 board, but a
generic configuration is introduced that can be used by other boards if
needed.

Signed-off-by: Manuel Argüelles <manuel.arguelles@nxp.com>

samples/subsys/task_wdt/boards/mr_canhubk3.overlay

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2023 NXP
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * FS26 watchdog cannot be used as hardware watchdog fallback on this SoC, since
+ * the SPI driver being used to communicate with the device, cannot transceive
+ * from interrupt context. In order to run this sample, FS26 must be started in
+ * DEBUG mode (see board documentation).
+ */
+&fs26_wdt {
+	status = "disabled";
+};

samples/subsys/task_wdt/prj_no_hw_fallback.conf

@@ -0,0 +1,8 @@
+CONFIG_LOG=y
+CONFIG_LOG_MODE_IMMEDIATE=y
+
+CONFIG_WATCHDOG=n
+
+CONFIG_TASK_WDT=y
+
+CONFIG_THREAD_NAME=y

samples/subsys/task_wdt/sample.yaml

@@ -1,23 +1,28 @@
 sample:
   name: Task Watchdog Subsytem Sample
+common:
+  tags: subsys
+  harness: console
+  harness_config:
+    type: multi_line
+    ordered: true
+    regex:
+      - "Task watchdog sample application."
+      - "Control thread started."
+      - "Main thread still alive..."
+      - "Control thread getting stuck..."
+      - "Task watchdog channel 1 callback, thread: control"
+      - "Resetting device...(.*)"
+      - "Task watchdog sample application."
+  depends_on: watchdog
+  platform_exclude:
+    - s32z270dc2_rtu0_r52
+    - s32z270dc2_rtu1_r52
 tests:
   sample.subsys.task_wdt:
-    tags: subsys
-    harness: console
-    harness_config:
-      type: multi_line
-      ordered: true
-      regex:
-        - "Task watchdog sample application."
-        - "Control thread started."
-        - "Main thread still alive..."
-        - "Control thread getting stuck..."
-        - "Task watchdog channel 1 callback, thread: control"
-        - "Resetting device...(.*)"
-        - "Task watchdog sample application."
-    depends_on: watchdog
     integration_platforms:
       - nucleo_g474re
-    platform_exclude:
-      - s32z270dc2_rtu0_r52
-      - s32z270dc2_rtu1_r52
+  sample.subsys.task_wdt.no_hw_fallback:
+    extra_args: CONF_FILE="prj_no_hw_fallback.conf"
+    platform_allow:
+      - mr_canhubk3