Makes section title clickable and collapsible

Closes #63181

See merge request gitlab-org/gitlab-ce!31571

Add missing report-uri to CSP config

See merge request gitlab-org/gitlab-ce!31593

- This will make it easy to identify the project even if admins change
the name of the project or move it.

This is supported in Rails 5.2, although it may be
deprecated in the future by reports-to.

https://gitlab.com/gitlab-org/gitlab-ce/issues/62971

Adds support to EnvironmentsController#metrics_dashboard
for the following params: group, title, y_label
These params are used to uniquely identify a panel on
the metrics dashboard.

Metrics are stored in several places, so this adds
utilities to find a specific panel from the database
or filesystem depending on the metric specified.

Also moves some shared utilities into separate classes,
notably default values and errors.

In the job log, if the user clicks the section title
the job log section will be collapsed

Squash this commit and reword before merging..

Add support for Content-Security-Policy

Closes #65330

See merge request gitlab-org/gitlab-ce!31402

Kubernetes deployments on new clusters will now have
a separate namespace per project environment, instead
of sharing a single namespace for the project.

Behaviour of existing clusters is unchanged.

All new functionality is controlled by the
:kubernetes_namespace_per_environment feature flag,
which is safe to enable/disable at any time.

- Closes #60024

- Change PrometheusClient.new to accept a base url instead of an
  already created RestClient

- Use Gitlab::HTTP in PrometheusClient instead of creating RestClient
  in PrometheusService

- Move http_options from PrometheusService to
  PrometheusClient (follow_redirects: false)

- ensure that base urls don't have the trailing slash

- Created a `PrometheusClient#url` method that might not be strictly
  required

- Change rescued exceptions from RestClient::* to
  HTTParty::ResponseError where possible and StandardError for the
  rest