[TRNT-4139] Allow serving Trento from a subpath

[antgamdia]

Description

Following up on trento-project/web#3948, this PR introduces the changes required for letting Trento know the subpath we are using in the Ingress rule. For example, to serve foo.example.com/trento, we'd just need to do:

ingress:
  hosts:
    - host: "foo.example.com"
      paths:
        - path: /trento
        # ...