net: lwm2m: Test compilation with data cache enabled

This should allow an issue such as #86681 to be found earlier for a not
widely used config.

Signed-off-by: Etienne de Maricourt <edmecomemail@gmail.com>

samples/net/lwm2m_client/overlay-data-cache.conf

@@ -0,0 +1,5 @@
+CONFIG_ZCBOR=y
+CONFIG_ZCBOR_CANONICAL=y
+CONFIG_LWM2M_RW_SENML_CBOR_SUPPORT=y
+CONFIG_POSIX_TIMERS=y
+CONFIG_LWM2M_RESOURCE_DATA_CACHE_SUPPORT=y

samples/net/lwm2m_client/sample.yaml

@@ -64,6 +64,18 @@ tests:
     tags:
       - net
       - lwm2m
+  sample.net.lwm2m_client.data_cache:
+    harness: net
+    depends_on: netif
+    extra_args: EXTRA_CONF_FILE=overlay-data-cache.conf
+    platform_allow:
+      - qemu_x86
+      - native_sim
+    integration_platforms:
+      - qemu_x86
+    tags:
+      - net
+      - lwm2m
   sample.net.lwm2m_client.wnc_m14a2a:
     harness: net
     extra_args: SHIELD=wnc_m14a2a