swapcli version and swapd version RPC call
The `swapcli version` command would report the following:
* The version of `swapcli` itself
* The version of `swapd` (assuming swapcli's version is compatible enough to query it from `swapd`)
* P2p protocol version (since 2 versions of `swapd` may be protocol compatible)
* The current environment (dev, stagenet, mainnet)
* The swap creator address that `swapd` is currently using (as the user may have configured it to an alternative address on start)

Maybe values. The risk in including these is that they could cause the whole RPC version request to fail:
* monerod version
* eth chainID (which is already in the protocol ID) and network ID?
* time delta since the last XMR and ETH block (probably nice to have, but arguably not version information)