Support PCA dpnp implementation on dpbench

[adarshyoga]

The dpnp implementation of the PCA algorithm has several calls that are currently not supported in dpnp - dpnp.mean(axis=0), dpnp.linalg.eigh, etc. These functions need to supported in dpnp to run PCA workload in dpbench.

How to reproduce:

1. Follow instructions to setup dpbench
2. Run PCA - python -c "import dpbench; dpbench.run_benchmark(\"pca\")