kie-issues#892: Collapsing and expanding Decision Services

[aswathitv]

Closes kie#892

• Added collapse button to expanded decision services
• Expanding and collapsing of decision services on click of respective buttons
• Hiding and showing of contained decisions
• For decision services with conflicted decisions, expand button is greyed out so that there are no other expanded Decision Services with conflicted decisions.

[tiagobento]

@aswathitv Thanks for the PR! Some comments from my side:

• Adding conflictedNodes to the Store forces you to update it, which is error-prone and won't work that well depending on how you're adding things to a DRD. Instead, create a new computed value so that the list of all conflicting Decisions inside Decision Services is available for you at all times.
• Great change on the minimum node sizes for when adding a Decision Service to a DRD requires it to be collapsed from the start.