Promote fast-forward

Related to https://gitlab.com/gitlab-org/gitlab-ee/issues/2624

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Design

There is a banner under the merge requests settings(CE).

Promote trial or license activation for regular EE on-prem sites.

• Admin

• Having Start trial button.
• Having x button. --> If click it, the banner will be closed.
• Learn more --> Link to the document, so users can know more about the feature.
• Copy:

Improve Merge Requests with Fast-forward merge.

If you prefer a linear Git history and a way to accept merge requests without creating merge commits, 
you can configure this on a per-project basis. Learn more

• Regular user

• Copy:

Improve Merge Requests with fast-forward. Contact your Administrator to upgrade the license.

If you prefer a linear Git history and a way to accept merge requests without creating merge commits, 
you can configure this on a per-project basis. Learn more

Admin	Regular users

For GitLab.com the feature promotion needs to go to purchase a GitLab.com plan

• Admin

• Having Upgrade now button.
• Copy:

Upgrade license to activate Fast-forward merge.

• Regular users

• Copy:

Contact your Administrator to upgrade license to activate Fast-forward merge. 

Admin	Regular users