Check unbonding delegation when creating withdraw tx

[jrwbabylonlab]

When we create the withdraw early unbonded transaction, we require unbonding tx as the input. However, we never check the legibility of the transaction to make sure it's indeed is the unbonding tx and pointing to the right staking tx that we want to withdraw from.

The scope of this issue is to add such check in the btc-staking-ts lib and make sure have sufficient test coverages

[jrwbabylonlab]

After looking deep into the code, it does not seem we need such check as the btc will reject if the input does not match from previous tx output anyway.