Merge bitcoindevkit/bdk#1084: Enhance bdk chain structures

1ff806c67f fix(chain)!: rm weird `From` impl (志宇)
d43ae0231f refactor: improve docs, cleanup unnecessary types and improve code (Vladimir Fomene)
4104206980 feat: impl Append for lots of tuples (LLFourn)
c56728ff13 refactor: Remove `scan` and `scan_txout` from SpkTxoutIndex and KeychainTxoutIndex (Vladimir Fomene)
32c40ac939 feat(electrum)!: change signature of `ElectrumExt` (志宇)
a28748c339 refactor: Implement Default for WalletUpdate (Vladimir Fomene)
f42f8b8ff1 refactor: Allow for no chain update (Vladimir Fomene)
68572bfd2e refactor: move WalletChangeset to wallet module (Vladimir Fomene)
2392e50fd9 refactor: Move WalletUpdate to wallet module (Vladimir Fomene)
7c12dc9942 refactor: Remove ForEachTxout trait (Vladimir Fomene)
6bcbb93233 refactor: Edit ElectrumExt not to use WalletUpdate (Vladimir Fomene)

Pull request description:

  ### Description

  Fixes #1061

  ### Changelog notice

  - Move WalletUpdate to the wallet module
  - Remove ForEachTxout trait completely
  - Refactor ElectrumExt to not use WalletUpdate.

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

ACKs for top commit:
  evanlinjin:
    ACK 1ff806c67f

Tree-SHA512: 05349713af9d2efa14a522ceaabb7513bb437d786adf2f93055765589a67e4eb68bda36ff415aeba07816c4d30988d4d55bac018e7697019270a219105ed65a2

example-crates/wallet_esplora_blocking/src/main.rs

@@ -7,8 +7,7 @@ use std::{io::Write, str::FromStr};
 
 use bdk::{
     bitcoin::{Address, Network},
-    chain::keychain::WalletUpdate,
-    wallet::AddressIndex,
+    wallet::{AddressIndex, Update},
     SignOptions, Wallet,
 };
 use bdk_esplora::{esplora_client, EsploraExt};
@@ -58,10 +57,10 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         client.scan_txs_with_keychains(keychain_spks, None, None, STOP_GAP, PARALLEL_REQUESTS)?;
     let missing_heights = wallet.tx_graph().missing_heights(wallet.local_chain());
     let chain_update = client.update_local_chain(prev_tip, missing_heights)?;
-    let update = WalletUpdate {
+    let update = Update {
         last_active_indices,
         graph: update_graph,
-        ..WalletUpdate::new(chain_update)
+        chain: Some(chain_update),
     };
 
     wallet.apply_update(update)?;