Add grouping option to the key of the filtered-search

What does this MR do and why?

• Add to Security inventory page the ability to define grouping by keys (titles), not just in the value as today.
• Create a new FF called security_inventory_filtering
• Note: only after: gitlab-org/gitlab-services/design.gitlab.com!4698 (closed) (Gitlab-UI MR repository) is merged, you will see the UI as expected.

References

Feature flag - #552224

Gitlab-UI repository MR - gitlab-org/gitlab-services/design.gitlab.com!4698 (closed)

Gitlab repository Issue - #537455 (closed)

Epic link: &16484

Design link: #515955 (closed)

Screenshots or screen recordings

Before	After
Screen Recording 2025-06-29 at 22.46.14.mov	Screen Recording 2025-06-29 at 22.03.19.mov

How to set up and validate locally

1. Enable FF: Feature.enable(:security_inventory_dashboard, group) and Feature.enable(security_inventory_filtering, group)
   1. To get the group parameter, use group = Group.find(33) with any group ID.
2. Create a sub group under this group
3. Enable one of the scanners project under your sub group and run the pipeline.
4. Visit the inventory page for that group: http://gdk.test:3000/groups/flightjs/-/security/inventory
5. Click on the search bar and valid that everything looking as expected.
6. Note: only after: gitlab-org/gitlab-services/design.gitlab.com!4698 (closed) (Gitlab-UI MR repository) is merged, you will see the UI as expected.

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #537455 (closed)