Add hard_fork to get_info rpc request

It's simple to add and saves a call to HARD_FORK_INFO when all you care
about is the hf number (and not the other hard fork details).

src/rpc/core_rpc_server.cpp

@@ -373,6 +373,8 @@ namespace cryptonote { namespace rpc {
     res.top_block_hash = tools::type_to_hex(top_hash);
     res.target_height = m_core.get_target_blockchain_height();
 
+    res.hard_fork = m_core.get_blockchain_storage().get_network_version();
+
     bool next_block_is_pulse = false;
     if (pulse::timings t; pulse::get_round_timings(m_core.get_blockchain_storage(), res.height, prev_ts, t)) {
       res.pulse_ideal_timestamp = tools::to_seconds(t.ideal_timestamp.time_since_epoch());

src/rpc/core_rpc_server_commands_defs.cpp

@@ -299,6 +299,7 @@ KV_SERIALIZE_MAP_CODE_BEGIN(GET_INFO::response)
   KV_SERIALIZE(pulse_target_timestamp)
   KV_SERIALIZE(difficulty)
   KV_SERIALIZE(target)
+  KV_SERIALIZE_ENUM(hard_fork)
   KV_SERIALIZE(tx_count)
   KV_SERIALIZE(tx_pool_size)
   KV_SERIALIZE(alt_blocks_count)

src/rpc/core_rpc_server_commands_defs.h

@@ -622,6 +622,7 @@ namespace rpc {
       uint64_t pulse_target_timestamp;      // For pulse blocks this is the target timestamp of the next block, which targets 2 minutes after the previous block but will be slightly faster/slower if the previous block is behind/ahead of the ideal timestamp.
       uint64_t difficulty;                  // Network difficulty (analogous to the strength of the network).
       uint64_t target;                      // Current target for next proof of work.
+      hf hard_fork;                         // Current network hard fork version
       uint64_t tx_count;                    // Total number of non-coinbase transaction in the chain.
       uint64_t tx_pool_size;                // Number of transactions that have been broadcast but not included in a block.
       std::optional<uint64_t> alt_blocks_count;            // Number of alternative blocks to main chain.