Network policy editor drawer

What does this MR do?

This MR implements a new policy drawer for the upcoming policy editor(&3403 (closed)). This new drawer contains policy overview and is only visible when a feature flag is enabled and selected policy has kind of CiliumNetworkPolicy.

I have also included a small fix for the description field of a policy into toYaml and fromYaml helpers.

Screenshots

without feature flag	with regular policy	with cilium policy	with cilium policy yaml tab

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