Modal and banner designs for project label and project milestone promotion

As part of our current efforts to change all of the modals to the new design, the promote label/milestone design needs to be updated to be consistent

Curently we only have change the copy text from the issue https://gitlab.com/gitlab-org/gitlab-ce/issues/40920

When promoting on project milestones list page, remain (refreshing if necessary) on project milestones list page, with the banner message.
When promoting on the project milestone page, redirect to the group milestone page of the new group milestone. Use same banner message.

	Labels	Milestones (EE)	Milestones (CE)
Modal design		The link should go to https://docs.gitlab.com/ee/user/project/milestones/. These docs will indicate missing features.
Modal title	Promote ~Discussion to group label?`	Promote 9.5 to group milestone?	Promote 9.5 to group milestone?
Modal body	Promoting [label] will make it available for all projects inside [Group name]. Existing project labels with the same name will be merged. This action cannot be reversed.	Promoting [milestone] will make it available for all projects inside [Group name]. Existing project milestones with the same name will be merged.[New Paragraph] Group milestones are currently missing features such as burndown charts. You will not have these features once you've promoted a project milestone. They will be available in future releases. [New Paragraph] This action cannot be reversed.	Promoting [milestone] will make it available for all projects inside [Group name]. Existing project milestones with the same name will be merged. This action cannot be reversed.

Can only promote on project lists page. When promoting, remain (refreshing if necessary) on project labels/milestones list page, with the banner message, which has a link to the group object.

	Labels	Milestones
Banner design
Copy	Discussion promoted to group label	9.1 promoted to group milestone

Edited Feb 22, 2018 by Hazel Yang