Automate the PCA matrix update process

During the ingestion process we could save the generated PCA matrix to a fixed location in a GCS bucket and make sure the api can be configured to read the PCA matrix from a location in a GCS bucket with some level of caching and a periodic refresh mechanism. That would eliminate the need to manually update the PCA matrix and redeploy the api every time we ingest new data.

@geohacker mentioned that he likes having the PCA matrix in the repo. If that's a must, we can set up a github action to raise a PR to update the PCA matrix whenever the PCA matrix is regenerated.

cc @leothomas @willemarcel