Merge bitcoindevkit/bdk-cli#202: Kyoto: Remove connection requirement to send tx

3b60b7b2321c7a9827f693e50431c87dd3992cae fix(kyoto): remove conn requirement to send tx (rustaceanrob)

Pull request description:

  Kyoto now holds on to a transaction internally until it is successfully broadcast, so we can broadcast the transaction immediately once the node starts up, and wait for a confirmation or 30 second timeout

  Successful test on Signet. Note that `Testnet4` still has the difficulty adjustment bug when loading block headers from storage.

  ### Checklists

  #### All Submissions:

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

  #### New Features:

  * [ ] I've added tests for the new feature
  * [ ] I've added docs for the new feature
  * [ ] I've updated `CHANGELOG.md`

  #### Bugfixes:

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

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Tree-SHA512: e1ad420440bad12b42847f09cc564e9fcc292c5acf12ac173560652c85a3fcf802052d20206bef7a8615d6beb93519c83c519dc086d8604656f088e78ef424b4