Add policy source information for project-level

What does this MR do and why?

Add policy source information for project-level

• for scan execution policies at the project level add source information to the table
• show whether the policy is inherited or not
• simplify table column logic
• update tests

Changelog: added

EE: true

Related to #345313 (closed)

Screenshots or screen recordings

Page	Before	After
Child project
Child project - inherited policy	-
Child group - non-inherited policy	-
Child group - inherited policy	-

How to set up and validate locally

1. Enable :group_level_security_policies feature flag
2. Upload a GitLab Ultimate license
3. Navigate to a group => Security & Compliance => Policies and assign a policy project with policies in it (using Update policy project selection for groups (!86981 - merged), but this MR is not dependent on it)
4. Navigate to a project in that group => Security & Compliance => Policies and assign a different policy project with policies in it
5. Verify the inheritance

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.