[RPC] Return RandomX seed and ProgPow epoch also if no miningaddress is set

[us77ipis]

The getblocktemplate rpc, should always include the RandomX seed (if a RandomX template is requested) and the ProgPow epoch (if a ProgPow template is requested), also if no miningaddress was specified in the config.

[Zannick]

utACK df354a8

[barrystyle]

Wouldn't this be a bit pointless if pprpcheader isn't returned?
This hash cannot be calculated without the miningaddress set, as it is required for the coinbase transaction to be formed in CreateNewBlock (in miner.cpp).

[us77ipis]

For example a mining pool which builds the blocks from scratch needs the epoch information but not the pprpcheader nor does it need to set a miningaddress in the daemon because it is set externally while building the coinbase transaction like you said.