Show item storage in Capacity Metrics App

[frithjof_v]

Make it possible to see storage consumption at Item level in the Capacity Metrics App.

At the moment, we can only see storage consumption at Workspace level, and this makes it difficult to pinpoint exactly which items (lakehouses, warehouses) consume most storage in our workspace.

Displaying the storage size (gigabytes) at Item level would increase the usability of the Storage page in Capacity Metrics App.

[Chris_Novak1]

Reviewing requirement with OneLake team.