Name log fields, metrics and the Core Rule Set package for what they are (closes #192)

Log field, metric, action and event names now say what they count
and, for timings, the unit. Package internal/waf is internal/coreruleset.

Model: opus-5-5

internal/discriminator/health_test.go

@@ -21,7 +21,8 @@ func TestHealthEndpointCountsTowardNoLimit(t *testing.T) {
 	)
 
 	for range healthChecks {
-		got := s.adminRequest("", http.MethodGet, discriminator.HealthPath, "", http.StatusOK)
+		got := s.ownEndpointRequest("", http.MethodGet, discriminator.HealthPath, "",
+			http.StatusOK)
 
 		if string(got.body) != "ok\n" || got.header.Get("Content-Type") != contentType {
 			t.Errorf("health endpoint answered %q with Content-Type %q, want ok "+