Implement more comprehensive `TransactionFlag` checks in each Transaction builder

[sappenin]

We should implement more comprehensive flag checks as preconditions in each Transaction builder.

For example, #690 introduce the ability to get TransactionFlags from the Transaction interface. To be fully correct, we would want to add precondition checks to each Transaction sub-class to make sure that transactions with the tfInnerTransaction flag didn't also include a signature, like this:

 @Value.Check
  default void vaidateInner(){
    if (flags().tfInnerBatchTxn()) {
      Preconditions.checkArgument(this.transactionSignature().isEmpty(),
        "Inner transaction must not have a transaction signature."
      );
      Preconditions.checkArgument(this.signingPublicKey().equals(PublicKey.EMPTY_PUBLIC_KEY),
        "Inner transaction must not have a signing public key."
      );
    }
  }

In addition, there are other flag checks that we might want to introduce additional checks around flags that are not allowed in OfferCreate. See the checks in xrpl-js for VaultCreate or the checks in NFTokenCreateOffers where xrpl-js checks certain conditions that xrpl4j does not.

[sappenin]

If we decide that this change is warranted, we likely want to revisit whether or not we make Transaction generic, to specify a single flags method through the whole hierarchy. The new signature would be like this:

public interface Transaction<F extends TransactionFlags> {

Note this would unwind the rationale for the changes made in #690 (see this developer note)