net: prometheus: Add more parameters to metric macros

Add collector parameter to metric creation macros so that it
is possible to bind the metric to collector already at built
time.

Also add optional user_data to metric macro calls so that user
can add optional data there. This will be used by network statistics
Prometheus support in subsequent commits.

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>

tests/net/lib/prometheus/collector/src/main.c

@@ -10,7 +10,7 @@
 #include <zephyr/net/prometheus/collector.h>
 
 PROMETHEUS_COUNTER_DEFINE(test_counter_m, "Test counter",
-			  ({ .key = "test_counter", .value = "test" }));
+			  ({ .key = "test_counter", .value = "test" }), NULL);
 
 PROMETHEUS_COLLECTOR_DEFINE(test_custom_collector);
 
@@ -31,9 +31,11 @@ ZTEST(test_collector, test_prometheus_collector_register)
 	prometheus_collector_register_metric(&test_custom_collector, &test_counter_m.base);
 
 	counter = (struct prometheus_counter *)prometheus_collector_get_metric(
-		&test_custom_collector, "test_counter");
+		&test_custom_collector, "test_counter_m");
 
-	zassert_equal(counter, &test_counter_m, "Counter not found in collector");
+	zassert_equal_ptr(counter, &test_counter_m,
+			  "Counter not found in collector (expected %p, got %p)",
+			  &test_counter_m, counter);
 
 	zassert_equal(test_counter_m.value, 0, "Counter value is not 0");
 

tests/net/lib/prometheus/counter/src/main.c

@@ -9,7 +9,8 @@
 #include <zephyr/net/prometheus/counter.h>
 
 PROMETHEUS_COUNTER_DEFINE(test_counter_m, "Test counter",
-			  ({ .key = "test_counter", .value = "test" }));
+			  ({ .key = "test_counter", .value = "test" }),
+			  NULL);
 
 /**
  * @brief Test prometheus_counter_inc

tests/net/lib/prometheus/gauge/src/main.c

@@ -9,7 +9,7 @@
 #include <zephyr/net/prometheus/gauge.h>
 
 PROMETHEUS_GAUGE_DEFINE(test_gauge_m, "Test gauge",
-			({ .key = "test", .value = "gauge" }));
+			({ .key = "test", .value = "gauge" }), NULL);
 
 /**
  * @brief Test prometheus_gauge_set

tests/net/lib/prometheus/histogram/src/main.c

@@ -9,7 +9,7 @@
 #include <zephyr/net/prometheus/histogram.h>
 
 PROMETHEUS_HISTOGRAM_DEFINE(test_histogram_m, "Test histogram",
-			    ({ .key = "test", .value = "histogram" }));
+			    ({ .key = "test", .value = "histogram" }), NULL);
 
 /**
  * @brief Test prometheus_histogram_observe

tests/net/lib/prometheus/summary/src/main.c

@@ -9,7 +9,7 @@
 #include <zephyr/net/prometheus/summary.h>
 
 PROMETHEUS_SUMMARY_DEFINE(test_summary_m, "Test summary",
-			  ({ .key = "test", .value = "summary" }));
+			  ({ .key = "test", .value = "summary" }), NULL);
 
 /**
  * @brief Test prometheus_summary_observe