Updating the BDK version creates some breaking change.

One of such change probably requires modification of BDK to expose a
new function to fetch scriptpubkey from a txid.

Used ureq version of esplora to remove async related complexities.

BDK v0.10.0 adds a stop_gap parameter to electrum config.

Esplora ureq version requires having new cli args.

Adds esplora-reqwest capability from bdk.
Allows to use async https connections with esplora from bdk-cli.

Recent update in BDK esplora backend allows it to connect with SOCKS5
proxy.

This change adds proxy option to esplora configuration.
Updates Proxy_Opts feature guard to enable it for esplora feature.