setup regtest environment for testing and developing

[ChrisSon15]

To test and develop the protocol, we need an test environment, which set up a network on docker to do the transactions. I should run locally and include a bitcoind and electrs installation and setting up 2 wallets and and explorer. There should be a script to fund the wallets.
BDK is endorsing Nirigi for this. https://bitcoindevkit.org/bdk-cli/regtest/