Add endpoint to provide a list of detected licenses for filtering

What does this MR do and why?

This change adds an endpoint for the Group level Dependency List to get a list of detected software licenses withing a group hierarchy. This filter is only available to group hierarchies that are below a specific threshold.

#422293 (closed)

SELECT DISTINCT "sbom_occurrences"."licenses"
FROM "sbom_occurrences"
WHERE "sbom_occurrences"."project_id" IN (
  SELECT "projects"."id"
  FROM "projects"
  WHERE "projects"."namespace_id" IN (
    SELECT namespaces.traversal_ids[array_length(namespaces.traversal_ids, 1)] AS id
    FROM "namespaces"
    WHERE "namespaces"."type" = 'Group'
    AND (traversal_ids @> ('{9970}'))
  )
  AND "projects"."marked_for_deletion_at" IS NULL
  AND "projects"."pending_delete" = FALSE
)
ORDER BY "sbom_occurrences"."licenses" ASC
LIMIT 100 OFFSET 0;

Time: 297.758 ms
  - planning: 9.632 ms
  - execution: 288.126 ms
    - I/O read: 0.000 ms
    - I/O write: 0.000 ms

Shared buffers:
  - hits: 62244 (~486.30 MiB) from the buffer pool
  - reads: 0 from the OS file cache, including disk I/O
  - dirtied: 0
  - writes: 0

https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/22853/commands/73727

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