Prep lightning-persister for export in the C bindings

[TheBlueMatt]

No description provided.

[codecov]

Codecov Report

Merging #874 (3fdf252) into main (8088e4b) will increase coverage by 0.02%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##             main     #874      +/-   ##
==========================================
+ Coverage   90.20%   90.22%   +0.02%     
==========================================
  Files          55       55              
  Lines       28913    28912       -1     
==========================================
+ Hits        26080    26086       +6     
+ Misses       2833     2826       -7     

Impacted Files	Coverage Δ
lightning-persister/src/lib.rs	94.06% <81.81%> (-0.90%)	⬇️
lightning/src/ln/functional_tests.rs	96.98% <0.00%> (+0.13%)	⬆️

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[TheBlueMatt]

Actually, @valentinewallace is there any reason for read_channelmonitors to be a HashMap to begin with? Its guaranteed to be unique because its file-based, and the OutPoint key is available in the ChannelMonitor anyway, plus when we go to read the ChannelManager they need to be in a HashMap, but without the BlockHash in the pair, so we have to move/convert it anyway?

[TheBlueMatt]

Completely dropped the second commit and replaced it with one which just exports a Vec instead, which the bindings already handle and which is just as useful for users.

[TheBlueMatt]

Only trivial style changes, will take after CI:

$ git diff-tree -U2 651f69b8 3fdf252b
diff --git a/lightning-persister/src/lib.rs b/lightning-persister/src/lib.rs
index c930de26..f6fbc635 100644
--- a/lightning-persister/src/lib.rs
+++ b/lightning-persister/src/lib.rs
@@ -58,5 +58,5 @@ where
 	K::Target: KeysInterface<Signer=Signer>,
 	F::Target: FeeEstimator,
-	L::Target: Logger
+	L::Target: Logger,
 {
 	fn write_to_file(&self, writer: &mut fs::File) -> Result<(), std::io::Error> {
@@ -96,5 +96,5 @@ impl FilesystemPersister {
 		K::Target: KeysInterface<Signer=Signer>,
 		F::Target: FeeEstimator,
-		L::Target: Logger
+		L::Target: Logger,
 	{
 		let path = PathBuf::from(data_dir);
@@ -106,5 +106,5 @@ impl FilesystemPersister {
 		&self, keys_manager: K
 	) -> Result<Vec<(BlockHash, ChannelMonitor<Signer>)>, std::io::Error>
-		where K::Target: KeysInterface<Signer=Signer> + Sized
+		where K::Target: KeysInterface<Signer=Signer> + Sized,
 	{
 		let path = self.path_to_monitor_data();
$