Serialize ProtocolVersions to storage

[drcpu-github]

At the moment whenever a protocol version is registered, its attributes are stored in a hashmap, but whenever a node is restarted it is not aware of these attributes anymore. Therefore the node assumes it is still in V1.7 after a restart, even though TAPI voted in V1.8 or the required stake amount for V2.0 was met, resulting in blocks etc not validating properly anymore.

[aesedepece]

This might do it, but haven't tried it yet:
aa2670d

Essentially, it puts the protocol info into the chain state, and makes sure it is read and written in the (allegedly) right places.

[aesedepece]

I'm not sure if 1_8 needs its own thing like this of 2_0, or the TAPI will be enough:

witnet-rust/node/src/actors/chain_manager/mod.rs

Lines 1053 to 1059 in aa2670d

	// Register the 2_0 protocol into chain state (namely, chain info) so that
	// the scheduled activation data eventually gets persisted into storage.
	chain_info.protocol.register(
	block_epoch + activation_delay,
	ProtocolVersion::V2_0,
	checkpoint_period,
	);

[drcpu-github]

I'm pretty sure it needs its own thing like this because TAPI is never persisted into storage either. AFAIK, if you restart your node during V1_8 (after all TAPI blocks have been confirmed and persisted into storage), it will forget it is in V1_8. I'll test it though.

[drcpu-github]

Added V1_8 into chain_info too for above reason: #2515

[aesedepece]

Done in aa2670d + ded83bb