Add Blockstream Privacy Analysis Script

[FrancisPouliot]

We should add this:

• when we get a response from a txid callback (get transaction, and other notifications)
• as a standalone api endpoint (privacy) whose object is a txid

[FrancisPouliot]

The scripts can be found here : https://github.com/Blockstream/esplora/blob/master/client/src/lib/privacy-analysis.js

I would like this to be a field in the "unconfirmed-tx" and "confirmed-tx" callback responses.

Optionally can be its own endpoint like "txprivacy" with a txid as argument