Extend Cluster Applications to allow installation of Prometheus

Description

Following our story of https://gitlab.com/gitlab-org/gitlab-ce/issues/38464 we add an easy installation of Prometheus in Cluster.

Proposal

Extend Cluster Applications with additional button: Prometheus and allow it to be installed.

We should use Helm Chart to install Prometheus in Cluster.

App name: Prometheus (link to https://prometheus.io/docs/introduction/overview/)

App description: Prometheus is an open-source monitoring system with [GitLab integration] to monitor deployed applications.

[GitLab integration] link: https://docs.gitlab.com/ce/user/project/integrations/prometheus.html

Links / references

• meta: https://gitlab.com/gitlab-org/gitlab-ce/issues/38464
• installation of ingress as reference: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/15185