chore(metrics): extend hb_metrics to abstract prometheus metrics

Create hb_metrics process that abstracts metrics subsystem implementation
and exposes the API for registering and interacting with metrics.

config/sys.config

@@ -0,0 +1,48 @@
+[
+	{hb, [
+		{metrics, [
+			#{
+				type => histogram,
+				name => "ao_cache_write_time",
+				description => "Histogram of write operation duration",
+				buckets => [5, 10, 100, 500, 1000]
+			},
+			#{
+				type => counter,
+				name => "ao_cache_read",
+				description => "Counts ao cache read operation"
+			},
+			#{
+				type => counter,
+				name => "ao_cache_write",
+				description => "Counts ao cache write operation"
+			},
+			#{
+				type => counter,
+				name => "ao_cache_list",
+				description => "Counts ao cache list operation"
+			},
+
+			#{
+				type => counter,
+				name => "ao_cache_resolve",
+				description => "Counts ao cache resolve operation"
+			},
+
+			#{
+				type => counter,
+				name => "ao_cache_type",
+				description => "Counts ao cache type operation"
+			},
+
+			#{
+				type => counter,
+				name => "ao_make_link",
+				description => "Counts ao_cache ao_make_link operation"
+			}
+
+
+
+		]}
+	]}
+].

rebar.config

@@ -45,11 +45,13 @@
 ]}.
 
 {shell, [
-	{apps, [hb]}
+	{apps, [hb]},
+	{config, "./config/sys.config"}
 ]}.
 
 {eunit, [
-	{apps, [hb]}
+	{apps, [hb]},
+	{config, "./config/sys.config"}
 ]}.
 
 {eunit_opts, [verbose]}.