Simplify http attrabute matching

In the past, we use Starlark script, it is over engineered and barely used.
By switching to simple key value string contains logic we can reduce core size about 0.7MB

app/router/config.go

@@ -1,6 +1,8 @@
 package router
 
 import (
+	"strings"
+
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/features/outbound"
 	"github.com/xtls/xray-core/features/routing"
@@ -143,11 +145,11 @@ func (rr *RoutingRule) BuildCondition() (Condition, error) {
 	}
 
 	if len(rr.Attributes) > 0 {
-		cond, err := NewAttributeMatcher(rr.Attributes)
-		if err != nil {
-			return nil, err
+		configuredKeys := make(map[string]string)
+		for key, value := range rr.Attributes {
+			configuredKeys[strings.ToLower(key)] = strings.ToLower(value)
 		}
-		conds.Add(cond)
+		conds.Add(&AttributeMatcher{configuredKeys})
 	}
 
 	if conds.Len() == 0 {