Support for multiple dependency link types between issues

Currently, our customers can select one Jira link type to display as a dependency within their Program.

In reality, many team of teams do not have standardisation of dependency links across teams and it can be hard to enforce all teams to use the same dependency type. 

There's also different types of dependencies that teams use to highlight hard and soft dependencies.

We're currently investigating how we could allow users to visualise more than one link type in a Program.