Merge bitcoindevkit/bdk#551: Fix sent calculation in the RPC backend

Merge bitcoindevkit/bdk#551: Fix sent calculation in the RPC backend

bfd0d13779003f11fa099a0b665052c18ce6e500 [blockchain] Fix `sent` calculation in the RPC backend (Daniela Brozzoni)
128c37595c5cfeacdb8e999da5795a9aa28ad67b [tests] Pass tx inputs to the testutils macro (Daniela Brozzoni)

Pull request description:

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  ### Description

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  ### 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

  #### Bugfixes:

  * [x] I've added tests to reproduce the issue which are now passing

ACKs for top commit:
  afilini:
    ACK bfd0d13779003f11fa099a0b665052c18ce6e500

Tree-SHA512: 1c214819c5dc1f1c30b1c6ef18a44a3013d587651890b26aecfc5203d128173fd91497337186bbee6934f77d3cfe1686e67b83ca6fe6e47b4c1d4b1dbcc656ee