Signer preloads transactions when Cardano transactions certification is not activated

[jpraynaud]

Why

The signer node imports the Cardano transactions, even if this type of data is not activated on the network. The expected behavior is to have the preloading triggered only when the aggregator advertises the Cardano transaction signed entity type.

What

Trigger the signer preloading of the Cardano transactions only if the aggregator advertises the CardanoTransactions type in its root route.

How

• TBD