Types required in bdk 1.0.0-beta.4

[thunderbiscuit]

Just keeping track of types we need as of the beta 2.

• [x] Address
• [x] Transaction
• [ ] Psbt
• [x] OutPoint
• [x] TxIn
• [x] TxOut
• [x] FeeRate

[rustaceanrob]

I'll work on TxIn

[rustaceanrob]

Next up is Transaction. I will have a look at what API surface we need for bdk-ffi and ldk-node