Merge bitcoindevkit/bdk#666: Various fixes to the `fee_amount` calculation in `create_tx`

419dc248b667db05295cd4c68347c4ef51f51023 test: Document `test_bump_fee_add_input_change_dust` (Daniela Brozzoni)
632dabaa07ef9c58926facf0af5190f62bb65d12 test: Check tx feerate with longer signatures (Daniela Brozzoni)
2756411ef7cf0415baf2f2401e2d5a78481d0aa1 test: Reproduce #660 conditions (Daniela Brozzoni)
50af51da5a5c906d8bf660d35a4f922ceb996068 test: Fix P2WPKH_FAKE_WITNESS_SIZE (Daniela Brozzoni)
ae919061e2b341ae74c90f0133ba392e835cb4e1 Take into account the segwit tx header when... ...selecting coins (Daniela Brozzoni)
7ac87b8f99fc0897753ce57d48ea24adf495a633 TXIN_BASE_WEIGHT shouldn't include the script len (Daniela Brozzoni)
ac051d7ae9512883e11a89ab002ad2d2c3c55c19 Calculate fee amount after output addition (Daniela Brozzoni)
00d426b88546a346820c102386cd1bfff82ca8f6 test: Check that the feerate is never below... ...the requested one in assert_fee_rate (Daniela Brozzoni)
42fde6d4575b4aea121286f884f712b1c1cf64be test: Check fee_amount in assert_fee_rate (Daniela Brozzoni)

Pull request description:

  ### Description

  This PR mainly fixes two bugs:
  1. TXIN_BASE_WEIGHT wrongly included the `script_len` (Fixes #160)
  2. We wouldn't take into account the segwit header in the fee calculation, which could have resulted in a transaction with a lower feerate than the requested one
  3. In tests we used to push 108 bytes on the witness as a fake signature, but we should have pushed 106 instead

  I also add a test to reproduce the conditions of #660, to check if it's solved. Turns out it's been solved already in #630, but if you're curious about what the bug was, here it is: https://github.com/bitcoindevkit/bdk/issues/660#issuecomment-1196436776
  ### 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:

  * [ ] This pull request breaks the existing API
  * [x] I've added tests to reproduce the issue which are now passing
  * [x] I'm linking the issue being fixed by this PR

ACKs for top commit:
  afilini:
    ACK 419dc248b667db05295cd4c68347c4ef51f51023

Tree-SHA512: c7b55342eac440a3607a16b94560cb9c08c4805c853432adfda8e21c5177f85d5a8afe0e7e61140e92c8f10934332459c6234fc5f1509ea699d97b1d04f030c6

diff --cc src/wallet/mod.rs
Simple merge