Permissions for vulnerabilities

What does this MR do?

A part of #13247 (closed)

Update permissions related to vulnerabilities. Basically, we want that :read_vulnerability policy to be "basic" policy and other related permissions should be inherited from it, like :read_project_security_dashboard. So in cases when we need to check if the user has access to vulnerabilities, we don't check anymore if the user has access to the security dashboard.

Permission levels are not changed.

Documentation will be in follow-up MR.

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

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