Add Pod Count as a Sortable Attribute in --sort Option

[neerajjose]

Currently, the kube-capacity tool provides sorting functionality for various attributes, including CPU and memory metrics, but it lacks the ability to sort by the number of pods. This feature would be useful for users who want to quickly identify nodes with the highest or lowest pod counts.

Proposed Enhancement:

• Add pod.count to the list of supported attributes for the --sort option.