Add last_local_balance_msats field

[Mirebella]

This PR adds last_local_balance_msats field. Solves #1898 .

I have a few open questions:

• what value should I assign to last_local_balance_msats, in file channel.rs at https://github.com/Mirebella/rust-lightning/blob/3eba0e2bbcb8547d561b175b1f19dd19565911b3/lightning/src/ln/channel.rs#L9591C1-L9591C33
• in mod.rs at https://github.com/Mirebella/rust-lightning/blob/3eba0e2bbcb8547d561b175b1f19dd19565911b3/lightning/src/events/mod.rs#L1538C6-L1538C44
  I saw that tlv fields are numbered differently(sometimes even numbers, sometimes odd numbers). I added my variable under number 11. Is that correct?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.87%. Comparing base (f7cc40e) to head (5d48d58).
Report is 132 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3235      +/-   ##
==========================================
+ Coverage   89.64%   90.87%   +1.23%     
==========================================
  Files         126      127       +1     
  Lines      102399   116414   +14015     
  Branches   102399   116414   +14015     
==========================================
+ Hits        91793   105792   +13999     
- Misses       7881     7993     +112     
+ Partials     2725     2629      -96     

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[Mirebella]

Does it look good?

[TheBlueMatt]

Basically looks good, just needs better docs.

[TheBlueMatt]

When you update the docs, please feel free to squash the commits down into one, but include more detail in the commit message - why was this change needed, what did the change do, any details about why the change was done in the way it was, etc.

[TheBlueMatt]

This basically LGTM, modulo the indentation note and the git commit message being missing. See https://cbea.ms/git-commit/ for a much, much, much longer discussion of how to write good commit messages.

[Mirebella]

Addressed all your points above, ready for review.

[TheBlueMatt]

Basicaly LGTM. Can you word-wrap your commit message so that no line is longer than ~70 chars? See-also https://cbea.ms/git-commit/ for commit message writing.

[TheBlueMatt]

nit, we usually tick our links so that they show up monospace

Suggested change

	/// For more accurate balances including fee information see [ChainMonitor::get_claimable_balances]
	/// For more accurate balances including fee information see [`ChainMonitor::get_claimable_balances`]

[vincenzopalazzo]

What Matt said regarding the commit, otherwise LGTM

[TheBlueMatt]

Went ahead and pushed the updates myself. They're docs-only so just gonna land:

$ git diff-tree -U2 2557e6b7e 3cd6ada3d
diff --git a/lightning/src/events/mod.rs b/lightning/src/events/mod.rs
index ebac6e4a9..2384a49db 100644
--- a/lightning/src/events/mod.rs
+++ b/lightning/src/events/mod.rs
@@ -1277,8 +1277,12 @@ pub enum Event {
 		/// Note that for instances serialized in v0.0.119 or prior this will be missing (None).
 		channel_funding_txo: Option<transaction::OutPoint>,
-		/// Local balance in msats when a channel is closed.
+		/// An upper bound on the our last local balance in msats before the channel was closed.
 		///
-		/// May overstate balance by pending outbound HTLCs and transaction fees.
-		/// For more accurate balances including fee information see [ChainMonitor::get_claimable_balances]
+		/// Will overstate our balance as it ignores pending outbound HTLCs and transaction fees.
+		///
+		/// For more accurate balances including fee information see
+		/// [`ChainMonitor::get_claimable_balances`].
+		///
+		/// This field will be `None` only for objects serialized prior to LDK 0.1.
 		last_local_balance_msats: Option<u64>,
 	},
@@ -1562,5 +1566,5 @@ impl Writeable for Event {
 			&Event::ChannelClosed { ref channel_id, ref user_channel_id, ref reason,
 				ref counterparty_node_id, ref channel_capacity_sats, ref channel_funding_txo,
-				ref last_local_balance_msats
+				ref last_local_balance_msats,
 			} => {
 				9u8.write(writer)?;

[tnull]

LGTM other than the field naming mentioned.

[TheBlueMatt]

Done

[vincenzopalazzo]

LGMT

[Mirebella]

@TheBlueMatt Thank you very much