Promote group webhooks

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

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Design

• On the Group -> Settings -> Webhooks page
• Having a full-width banner

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

Admin

• Having Start GitLab Enterprise Edition trial button.
• Having x button on the top-right corner. --> If click it, the banner will be closed.
• Read more

• Link to the document, so users can know more about the feature.
• Link: https://docs.gitlab.com/ce/user/project/integrations/webhooks.html

• Copy:

Add Group Webhooks and GitLab Enterprise Edition.

Webhooks allow you to trigger a URL if, for example, new code is pushed or a new issue is created. 
You can configure webhooks to listen for specific events like pushes, issues or merge requests. 

Group webhooks will apply to all projects in a group, allowing you to standardize webhook functionality across your entire group. [Read more]

Non-admin

• Additional 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 activate Group Webhooks. 

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

Non-admin

• Copy:

Upgrade your plan to activate Group Webhooks. 

{{ 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-webhook.svg