refactored configuration of perspectives

[sciros]

Now perspectives are expected to be a dict of dicts of dicts and the way endpoint information relates to perspective codes is clearer.
Basically like this:

perspectives_as_dict = {
    "us-east-1": {"caa_endpoint_info": {"arn": "arn:aws:acm-pca:us-east-1:123456789012:caa/us-east-1"},
                           "dcv_endpoint_info": {"arn": "arn:aws:acm-pca:us-east-1:123456789012:dcv/us-east-1"}},
    "eu-west-2": {"caa_endpoint_info": {"arn": "arn:aws:acm-pca:eu-west-2:123456789012:caa/eu-west-2"},
                             "dcv_endpoint_info": {"arn": "arn:aws:acm-pca:eu-west-2:123456789012:dcv/eu-west-2"}}
}

Note: in the FastAPI version of this, the endpoint info has "url" and "headers" instead of "arn".

[sciros]

I also moved the open-mpic-core dependency to the main PyPI index instead of test, in preparation to doing this for the FastAPI project as well.