feat: Support generating default routes pointing to the landing page

[CH3CHO]

Ⅰ. Describe what this PR did

Generate a default route pointing to the landing page provided by Higress Console when no Ingress resource matching following criteria is found:

• In a namespace watched by Higress Controller, depended on the value of global.watchedNamespace
  • global.watchedNamespace is empty: This criterion shall be ignored.
• Bound to an IngressClass watched by Higress Controller, depended on the value of global.ingressClass
  • global.ingressClass is empty: This criterion shall be ignored.
  • global.ingressClass is nginx: Only Ingress resources with ingressClassName set to nginx or left empty matches the criterion.
  • global.ingressClass is any other value: Only Ingress resources with the same ingressClassName with global.ingressClass matches the criterion.

Besides the changes above, this PR also adds a new all query parameters to the /v1/routes API, allowing callers to get all the Ingresses watched by the contoller, not only those in the same namespace with the console itself.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews