A Running list of bdk-cli demo ideas

with the `regtest-*` features and bdk-cli `repl` mode various multisig and other smart contracting situations can be demonstrated with bdk-cli..

Examle: Show an workflow of a Liquid like federation using a corresponding descriptor and bdk cli.

These demos can be recorded in various forms.
- Tutorial on the website.
- A demo videos in the youtube channel.
- Add it as a integration tests as both code level demo as well as consistency of these workflows with BDK API.

The general approach for a trial can be something like this
- Use the https://min.sc/ compiler to create your own weird descriptor.
- Split the descriptor for different parties involved in the compiler
- Start multiple wallet `repl` terminals with each parties descriptor. They will default connect to a single regtest node so all parties will be in sync
- Play around making transactions for various contract situations..

With this in mind we can start making a list of such interesting smart contracting situations with bitcoin scripts and demonstrate them out through BDK. Below is a list of basic ideas I imagined. Please comment below with more interesting contract ideas.

- [ ] Basic demo of a single sig wallet. (An test version of this is included in #102 )
- [ ] Basic 2-of-3 multisig demo
- [ ] Multisig with time locks. Something like @sandipndev cooked [here](https://bitcoindevkit.org/blog/hidden-power-of-bitcoin/#retention-bonus-smart-contract-with-bitcoin).
- [ ] A Liquid like federation demo
- [ ] An HTLC lighting contract demo. Playing out what exactly happens with with lighting state updates and penalty mechanisms.