Supports routing of modulo operation (mod) based on value of header

[lianglli]

基于请求Header取模的流量切分，可以指定具体匹配的header，当header值取模运算得到余数满足关系运算符的匹配条件，则将请求转发到指定的upstream。

如果 [header值] mod [除数] 关系运算符 [余数] 为真，那么路由规则生效，请求就会被转发到指定的upstream。

取模除数: [2, 100]; 关系运算符: "==, >, >=, <, <="; 取模余数: [0, 取模除数)。

如果除数，关系运算符和余数的取值范围非法，则路由规则降级为基于请求Header的流量切分。

无损动态生效，无需tengine reload。

[lianglli]

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    nginx.ingress.kubernetes.io/canary: "true"
    nginx.ingress.kubernetes.io/canary-by-header: header-test2
    nginx.ingress.kubernetes.io/canary-mod-divisor: "100"
    nginx.ingress.kubernetes.io/canary-mod-relational-operator: ==
    nginx.ingress.kubernetes.io/canary-mod-remainder: "1"
    nginx.ingress.kubernetes.io/ssl-redirect: "true"
  creationTimestamp: "2023-10-31T07:02:17Z"
  generation: 1
  name: tengine-ingress-hello-header-mod-with-actions-ing
  namespace: default
  resourceVersion: "28173436"
  uid: bfe4bc3b-d384-4718-8a0a-5f6c3e89ab68
spec:
  ingressClassName: opensource-ingress
  rules:
  - host: echo.w1.com
    http:
      paths:
      - backend:
          service:
            name: tengine-ingress-echo2-service
            port:
              number: 80
        path: /
        pathType: Prefix
  tls:
  - hosts:
    - echo.w1.com
    secretName: https-server-1
status:
  loadBalancer:
    ingress:
    - {}

........................................................................

$ curl -i -k -H "header-test2: 1001" https://echo.w1.com
HTTP/2 200 
server: Tengine/3.1.0
date: Wed, 01 Nov 2023 09:21:14 GMT
content-type: text/plain; charset=utf-8
content-length: 7
test-result: B0-236-564-29122
test-host: echo.w1.com
strict-transport-security: max-age=0
ups-target-key: default-tengine-ingress-echo2-service-80
x-protocol: HTTP/2.0
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000

echo ok