Rc/add metrics dashboard policy

What does this MR do?

Issue: #201924 (closed)

This MR adds a new policy for access to a projects metrics dashboard. Access to the metrics dashboard requires access to read_prometheus, read_environment and read_deployment. This MR also includes a couple small frontend fixes in support of this feature.

The table below shows permission permutations with this new feature flag. Bolded items are new permissions.

Project	Feature	User	Permission
Public	Private	anonymous	no
Public	Private	guest	no
Public	Private	reporter	yes
Public	Enabled	anonymous	yes
Public	Enabled	guest	yes
Public	Enabled	reporter	yes
Internal	Private	anonymous	no
Internal	Private	guest	no
Internal	Private	reporter	yes
Internal	Enabled	anonymous	no
Internal	Enabled	guest	yes
Internal	Enabled	reporter	yes
Private	Private	anonymous	no
Private	Private	guest	no
Private	Private	reporter	yes
Private	Enabled	anonymous	no
Private	Enabled	guest	no
Private	Enabled	reporter	yes

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team