Inputs and outputs on TxParams needs to be set before RandomTransaction creation

[TheMhv]

The TxParams struct currently uses InputParams and OutputParams for transaction creation, but it should use actual transaction inputs and outputs (Vec and Vec) to allow for more direct control over the random transaction generation process.

Proposed Changes

Update TxParams to use concrete transaction types:

pub struct TxParams {
    pub version: Option<Version>,
    pub lock_time: Option<LockTime>,
    pub input: Option<Vec<TxIn>>,
    pub output: Option<Vec<TxOut>>,
    pub private_key: Option<PrivateKey>,
    pub block_height: Option<u32>,
}