Implement the PartialEq trait of Transaction

[musitdev]

PartialEq of the Transaction struct should be implemented by hand using the Hash and/or signature.
All other fields are not needed for the equality.
Even the propagated field can generate some strange behavior because 2 tx can be equals with this field different.
Tx should only be identifier by its Hash and the Hash and signature field should be private.

We should add a new method to create the Tx with its Hash and signature so It should never be modified. Currently, a Tx can be created and not signed.

The payload shouldn't implement PartialEq. It's not useful and even can lead to some issue when you need to add a payload when equality doesn't really exist.