Request tags, with refusing and limits per tag (closes #175)

Each request gets tags, logged as `tags`: `asn=`, `country=`, one per `SWW_TAG_LISTS` list holding the client, `crowdsec`, `dnsbl=<zone>`, `abuseipdb` and `exploitsignature`. `SWW_TAG_DENY` refuses by tag and `SWW_TAG_LIMIT_PERCENT` lowers limits by tag. They replace `SWW_ASN_LIMIT_PERCENT`, `SWW_COUNTRY_LIMIT_PERCENT` and `SWW_DENIED_COUNTRIES`, with no aliases. A tag in those settings that nothing configured can give stops the start.

Judgement call: `SWW_ASN_LIMIT_PERCENT_URL` stays, its entries counting like `asn=` tags.
Judgement call: `SWW_TAG_LIMIT_PERCENT` also lowers byte limits, as the settings it replaces did.
Trips a reader: `sww_country_list_refusals_total` now counts only `SWW_EXCLUSIVELY_ALLOWED_COUNTRIES` refusals.

Model: opus-5-5

internal/discriminator/ratelimits_test.go

@@ -136,7 +136,7 @@ func TestRateLimitExemptPathsAreNeitherCountedNorRefused(t *testing.T) {
 		rateLimitPerMinute:   "1",
 		rateLimitExemptPaths: "/assets/,/favicon.ico",
 		denyNets:             denied,
-		deniedCountries:      "kp",
+		tagDeny:              denyKP,
 	})
 
 	// The answers are kept before the requests, so that none waits for
@@ -162,12 +162,12 @@ func TestRateLimitExemptPathsAreNeitherCountedNorRefused(t *testing.T) {
 	// /assets/, and breaks the limit.
 	s.request(client, "/assets", http.StatusForbidden, requestlog.ActionRateLimited)
 
-	// A ban, SWW_DENY_NETS and the country lists still refuse a path
-	// under a prefix.
+	// A ban, SWW_DENY_NETS and SWW_TAG_DENY still refuse a path under a
+	// prefix.
 	s.request(client, "/assets/app.js", http.StatusForbidden, requestlog.ActionBanned)
 	s.request(denied, "/assets/app.js", http.StatusForbidden, requestlog.ActionDenied)
 	s.request(fromKP, "/assets/app.js",
-		http.StatusForbidden, requestlog.ActionCountryDenied)
+		http.StatusForbidden, requestlog.ActionDenied)
 }
 
 func TestRateLimitCountsPathsThatAreNotExempt(t *testing.T) {