Add support for rpccookiefile in .env

[d6n13l0l1v3r]

Description:

To enhance security and align with best practices for bitcoind configurations, the implementation of importing/read the rpccookiefile for bitcoind is preferred over using traditional username/password authentication.

Problem:

Several tools, including corelíghthing, fulcrum, electrs, and others utilized in my Bitcoin full node, employ the rpccookiefile for enhanced security. However, there is an issue with integrating public-pool into this configuration as it lacks support for the rpccookiefile.

Proposed Solution:

Enable public-pool to utilize the rpccookiefile for bitcoind RPC authentication, allowing seamless integration with the security measures employed by other tools in the Bitcoin full node ecosystem.