Add consensus client to `fullnode.dappnode` feature

[pablomendezroyo]

The fullnode.dappnode is an alias added to the selected execution client by the user. This way, other dappnode packages can use this alias to make requests to the execution client. Add to the existing feature fullnode.dappnode the consensus client selected.

• fullnode.execution.dappnode => execution client selected
• fullnode.dappnode => execution client selected (for backwards compatibility)
• fullnode.consensus.dappnode => consensus client selected