Merge bitcoindevkit/bdk#1426: feat: add further `bitcoin::Amount` usage on public...

a03949adb0c38ba4c2f44b497871070c1a2170d2 feat: use `Amount` on `calculate_fee`, `fee_absolute`, `fee_amount` and others (Leonardo Lima)

Pull request description:

  builds on top of #1411, further improves #823

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  ### Description

  It further updates and adds the usage of `bitcoin::Amount` instead of `u64`.

  <!-- Describe the purpose of this PR, what's being adding and/or fixed -->

  ### Notes to the reviewers

  Open for comments and discussions.

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  of the PR were done in a specific way -->

  ### Changelog notice
  - Updated `CreateTxError::FeeTooLow` to use `bitcoin::Amount`.
  - Updated `Wallet::calculate_fee()`. to use `bitcoin::Amount`
  - Updated `TxBuilder::fee_absolute()`. to use `bitcoin::Amount`.
  - Updated `CalculateFeeError::NegativeFee` to use `bitcoin::SignedAmount`.
  - Updated `TxGraph::calculate_fee()`. to use `bitcoin::Amount`.
  - Updated `PsbUtils::fee_amount()` to use `bitcoin::Amount`.

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  <!-- See https://keepachangelog.com/en/1.0.0/ for examples -->

  ### 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

  #### New Features:

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

ACKs for top commit:
  storopoli:
    ACK a03949adb0c38ba4c2f44b497871070c1a2170d2

Tree-SHA512: abfbf7d48ec004eb448ed0a928e7e64b5f82a2ab51ec278fede4ddbff4eaba16469a7403f78dfeba1aba693b0132a528bc7c4ef072983cbbcc2592993230e40f