[Community Programs Renewal] Add a renew landing page

• add a new route /subscriptions/community_program/renew
• re-use templates that we build for CE subscription community_subscription_landing_page.vue

Buttons link to /subscriptions/community_program/my_renewal

• add a new route /subscriptions/community_program/my_renewal similar to https://gitlab.com/gitlab-org/customers-gitlab-com/-/blob/3dcda9b79ed975fc0b18f5f01941de4d38bff91b/app/controllers/subscriptions_controller.rb#L117

If user has only one subscription -> redirect directly to /subscriptions/community_program/A-SXXXXX/renew, if more than one -> to /subscriptions

Design issue: #2747 (closed)