Add support for expressing the sharing profile using JSON

[goodwillpunning]

Currently, data recipients cannot specify the location of a sharing profile using Azure Synapse FS (synfs: schema). Rather than expanding support for synfs and future, alternate schemas, it may be more flexible to allow data recipients to specify the sharing profile as a JSON object, passing it as an argument to the Python sharing client constructor. For example:

import delta_sharing

sharing_profile = {
  "shareCredentialsVersion": 1,
  "endpoint": "https://sharing.delta.io/delta-sharing/",
  "bearerToken": "dapi1234567890"
}
client = delta_sharing.SharingClient(sharing_profile)

While it could be argued that the sharing access token is now clear text, a secrets manager client, like Azure key vault client for Python, could be used to securely access the sharing token.