Merge bitcoindevkit/bdk#2081: Add spent/created_txouts to SPK and Keychain TxOut...

d17d85fd54a4783f50b08f1753b322b5060f2f4e feat(chain): add spent_txouts and created_txouts methods to SPK and keychain indexes (Steve Myers)
b347b033fd70e0a91339b79f89aac7acca03e8ab feat(chain): add input/output indices to sent_and_received_txouts (Steve Myers)
7777dfc08cd5141b50dc239abeca7316684f95d8 feat(chain): add sent_and_received_txouts method to SPK and keychain indexes (Steve Myers)

Pull request description:

  ### Description

  Implement spent_txouts and created_txouts methods on SpkTxOutIndex and KeychainTxOutIndex. These methods return SpentTxOut and CreatedTxOut structs allowing callers to access complete transaction output information including script pubkeys and values.

  ### Notes to the reviewers

  This info is useful to users who use the new WalletEvent data in bitcoindevkit/bdk_wallet#319. In particular to determine the addresses and amounts for TxOuts that are sent/spent or have been received in a newly seen or confirmed transaction. See: [bdk_wallet#319 comment](https://github.com/bitcoindevkit/bdk_wallet/pull/319#issuecomment-3630027488)

  If/when this PR is merged I'll make a corresponding one to `bdk_wallet::Wallet`.

  ### Changelog notice

  Added

  * New spent_txouts and created_txouts methods on SpkTxOutIndex and KeychainTxOutIndex.
  * New SpentTxOut and CreatedTxOut structs returned by spent_txouts and created_txouts functions.

  ### Checklists

  #### All Submissions:

  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)

  #### New Features:

  * [x] I've added tests for the new feature
  * [x] I've added docs for the new feature

ACKs for top commit:
  evanlinjin:
    ACK d17d85fd54a4783f50b08f1753b322b5060f2f4e

Tree-SHA512: 29c5e97b2f75ca026086a1a32549fd1ac7081614bf344daef05c232779e3e80e350e4aeaea35626e82591cdbb73e4bbd451516a82380e27834d0f8fd0a89cb63

diff --cc crates/chain/src/indexer/keychain_txout.rs
Simple merge