Add Block Filtering to bcli Plugin

[sangbida]

Problem

Currently, Core Lightning processes every transaction in every block, regardless of relevance to the node. chaintopology has a 30-second timer that makes an RPC calls to bcli. bcli acted as a simple wrapper around bitcoin-cli commands. All transactions processed by chaintopology regardless of relevance.

Proposed solution

• bcli polls bitcoind independently every 10/30 seconds and publishes a notification to lightningd
• bcli filters registers watches and filters blocks for relevant transactions
• bcli also sends mempool and fee rate notifications to lightnings.