Make ChannelMonitor clonable again

In general, we'd been moving away from ChannelMonitor being clonable,
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Author: TheBlueMatt

lightning/src/chain/channelmonitor.rs

@@ -267,7 +267,7 @@ struct HolderSignedTx {
 
 /// We use this to track counterparty commitment transactions and htlcs outputs and
 /// use it to generate any justice or 2nd-stage preimage/timeout transactions.
-#[derive(PartialEq)]
+#[derive(Clone, PartialEq)]
 struct CounterpartyCommitmentTransaction {
 	counterparty_delayed_payment_base_key: PublicKey,
 	counterparty_htlc_base_key: PublicKey,
@@ -623,6 +623,7 @@ impl Readable for ChannelMonitorUpdateStep {
 /// the "reorg path" (ie disconnecting blocks until you find a common ancestor from both the
 /// returned block hash and the the current chain and then reconnecting blocks to get to the
 /// best chain) upon deserializing the object!
+#[derive(Clone)]
 pub struct ChannelMonitor<Signer: Sign> {
 	latest_update_id: u64,
 	commitment_transaction_number_obscure_factor: u64,

lightning/src/ln/onchaintx.rs

@@ -240,6 +240,7 @@ impl Writeable for Option<Vec<Option<(usize, Signature)>>> {
 
 /// OnchainTxHandler receives claiming requests, aggregates them if it's sound, broadcast and
 /// do RBF bumping if possible.
+#[derive(Clone)]
 pub struct OnchainTxHandler<ChannelSigner: Sign> {
 	destination_script: Script,
 	holder_commitment: HolderCommitmentTransaction,