[3scale][2.11][LO-prio] Improve UI for changing Application plan for existing Application

User Story

As an API Provider, when I want to change an Application plan for an existing Application, I want to be able to easily find it.

Requirements

Everything that is explained in the mockups, plus:

• When 'Select Application plan' select is clicked, display all Application plans (except for the one the Application is currently subscribing to) for the Product in the dropdown menu (sort them alphabetically)

Resources

• Path: Product > Applications > Application Overview page – Change plan card
• Marvel

Acceptance Criteria

• All requirements have been implemented