Add optional auth for Bitcoin RPC connection to node

[deverickapollo]

Description

I request adding optional authentication fields to CW for connecting to a Bitcoin full node via RPC. This feature would allow users to enter their RPC credentials (username and password) when configuring a connection to their node. This aligns with the current implementation on the monero side of the wallet

Benefits

•	Enhanced compatibility with Bitcoin nodes requiring authentication.
•	Improved security for RPC connections by enabling credentialed access.
•	Broader appeal to power users who prefer managing their own nodes.

Proposed Implementation
• Add two optional fields in the Bitcoin node connection settings: Username and Password