bitcoindevkit/bdk

AI Summary: Implement a `populate_anchor_cache` method for the `BdkElectrumClient` in the Bitcoin Dev Kit (BDK) library to improve sync speed. This involves adding the method to the client, potentially creating a convenient method on the `TxGraph`, updating relevant examples in the `bdk` crate, and adding a convenient method to the `Wallet` in the `bdk_wallet` crate, along with updating its examples.