Promote features on repository settings page

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

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Design

• Having a banner on the top of Settings/Repository page.
• If the users don't have the EE license, Push Rules, Repository Mirroring, and Protected Branches sections will not show.
• Push Rules, Repository Mirroring, and Protected Branches will be promoted in the banner.

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

Admin

• Having Start GitLab Enterprise Edition trial button.
• Having X button. --> If click it, the banner will be closed.
• Copy / Link:

• Push Rules: https://gitlab.com/help/push_rules/push_rules.md#push-rules
• Repository Mirroring: https://docs.gitlab.com/ee/workflow/repository_mirroring.html
• Protected Branches: https://docs.gitlab.com/ee/user/project/protected_branches.html

Improve repositories with GitLab Enterprise Edition.

- [Push Rules]
Push Rules are defined per project so you can have different rules applied to 
different projects depends on your needs.

- [Repository Mirroring]
Repository Mirroring is a way to mirror repositories from external sources. It can be used to mirror all branches, 
tags, and commits that you have in your repository.

- [Protected Branches]
Permissions in GitLab are fundamentally defined around the idea of having read 
or write permission to the repository and branches. To prevent people from messing with 
history or pushing code without review, we've created protected branches.

Non-admin

• Copy:

Improve repositories with GitLab Enterprise Edition.  

{{As same as Admin copy}}

Contact your Administrator to upgrade your license.
 

Admin	Non-admin

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

Admin

• Having Upgrade your plan button.
• Copy:

Upgrade your plan to improve repositories with GitLab Enterprise Edition.

Non-admin

• Copy:

Upgrade your plan to improve repositories with GitLab Enterprise Edition.

{{As same as admin copy for regular EE on-prem sites}}

Contact your Administrator to upgrade your plan.

Admin	Non-admin

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SVG: graphic-push-rules.svg

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Other links:

• Promote push rules (#2921 (closed))
• Promote branch permissions (#2931 (closed))

mentioned in issue #2921 (closed)

mentioned in issue #2931 (closed)

mentioned in issue #2624 (closed)

changed the description

changed the description

changed the description

@hazelyang Excellent! See my other comments about calling the GitLab.com a "plan" not a license.

changed the description

Updated the copy and added the links in the description.

changed the description

added UX ready and removed UX labels

changed the description

changed milestone to %10.0

mentioned in issue #2930 (closed)

mentioned in merge request !2540 (merged)

Was also done with gitlab-org/gitlab-ee!2540

closed