Add new and edit pages for policies

What does this MR do?

Add new and edit pages for Policies sidebar, which is replacing the index/new/edit pages of the Threat Monitoring Policies tab

• link them to the policy editor page
• account for policy type needing to always be a parameter for the edit page
• condense policy type constants
• update tests
• update locale

How to setup and validate locally (strongly suggested)

1. Follow the Protect Onboarding task to be able to create network policies in kubernetes/cilium
2. Follow the scan execution creation snippet to create some scan execution policies
3. Turn on the :security_policies_orchestration_configuration feature flag
4. Navigate to Security & Compliance => Policies
5. Select New Policy or select a policy, wait for the drawer to open, and click Edit Policy

Screenshots or Screencasts (strongly suggested)

Title	Threat Monitoring Page (the page we are replicating/moving)	Policies Page (the page we are creating to replace)
List/Drawer (Container Network Policy)
List/Drawer (Container Cilium Policy)
List/Drawer (Scan Execution Policy)
New page
Edit page (Container Cilium Policy)		(there is more work to do on this one, but this MR provides the foundation)

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• 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

Related to #321884 (closed)