Add support for basic GPU cost prediction, support altered prediction API schema

[michaelmdresser]

What does this PR change?

Adds support for GPU cost prediction for standard AMD, Intel, and NVIDIA GPU plugins.

Does this PR rely on any other PRs?

• Builds on https://github.com/kubecost/kubectl-cost/pull/132
• Updates predict response schema from changes in https://github.com/kubecost/kubecost-cost-model/pull/1132

How does this PR impact users? (This is the kind of thing that goes in release notes!)

• Adds support in kubectl cost predict for GPU cost for standard AMD, Intel, and NVIDIA GPU plugins (amd.com/gpu, gpu.intel.com/i915, nvidia.com/gpu).

How was this PR tested?

→ go run cmd/kubectl-cost/kubectl-cost.go predict -f ./test/multi.yaml --window '2h'
+-------------------------------+------+-------+-----+------------+------------+-------------+-------------+
| WORKLOAD                      | CPU  | MEM   | GPU | CPU/MO     | MEM/MO     | GPU/MO      | TOTAL/MO    |
+-------------------------------+------+-------+-----+------------+------------+-------------+-------------+
| Deployment/nginx-deployment   | 9    | 6Gi   | 0   | 209.58 USD |  18.73 USD |    0.00 USD |  228.31 USD |
| Deployment/nginx-deployment-2 | 10   | 35Gi  | 0   | 232.87 USD | 109.23 USD |    0.00 USD |  342.10 USD |
| Pod/nginx-pod                 | 350m | 200Mi | 0   |   8.15 USD |   0.61 USD |    0.00 USD |    8.76 USD |
| Pod/nginx-pod                 | 350m | 200Mi | 3   |   8.15 USD |   0.61 USD | 2080.50 USD | 2089.26 USD |
+-------------------------------+------+-------+-----+------------+------------+-------------+-------------+
|                               |      |       |     | 458.75 USD | 129.18 USD | 2080.50 USD | 2668.42 USD |
+-------------------------------+------+-------+-----+------------+------------+-------------+-------------+

Have you made an update to documentation?

N/A