Move BlindedPayInfo into BlindedPaymentPath

[valentinewallace]

Rather than a BOLT 12 invoice's paths containing tuples of (BlindedPayInfo, BlindedPaymentPath), move the payinfo into the path itself.

[valentinewallace]

I think previously we were writing a length prefix for this, actually... Giving this a second look.

[TheBlueMatt]

Yea, used to be just a count and then elements, now its a yes/no flag followed by a length and the elements.

[valentinewallace]

Hm, the current code is passing a round trip ser test actually. I don't think there's a yes/no flag written for options, and optional_vec writes as WithoutLength, IIUC, so it might be fine? Will expand the test to include multiple hints..

[TheBlueMatt]

Ah, sorry, I was confusing myself on the option, but had missed its an IterableOnwed which doesnt have a length unlike a vec.

[valentinewallace]

Rebased.

[valentinewallace]

Sorry, one more rustfmt + fuzz fix to push.

[valentinewallace]

And one more doc test :(

diff --git a/lightning/src/offers/invoice.rs b/lightning/src/offers/invoice.rs
index d361c7ce4..40ee40090 100644
--- a/lightning/src/offers/invoice.rs
+++ b/lightning/src/offers/invoice.rs
@@ -29,8 +29,8 @@
 //! use lightning::util::ser::Writeable;
 //!
 //! # use lightning::ln::types::PaymentHash;
-//! # use lightning::offers::invoice::{BlindedPayInfo, ExplicitSigningPubkey, InvoiceBuilder};
-//! # use lightning::blinded_path::payment::BlindedPaymentPath;
+//! # use lightning::offers::invoice::{ExplicitSigningPubkey, InvoiceBuilder};
+//! # use lightning::blinded_path::payment::{BlindedPayInfo, BlindedPaymentPath};
 //! #
 //! # fn create_payment_paths() -> Vec<BlindedPaymentPath> { unimplemented!() }
 //! # fn create_payment_hash() -> PaymentHash { unimplemented!() }

[codecov]

Codecov Report

Attention: Patch coverage is 97.29730% with 6 lines in your changes missing coverage. Please review.

Project coverage is 89.69%. Comparing base (fb4403f) to head (4ef83a0).
Report is 4 commits behind head on main.

Files	Patch %	Lines
lightning/src/blinded_path/payment.rs	88.57%	1 Missing and 3 partials ⚠️
lightning/src/offers/invoice.rs	95.65%	0 Missing and 1 partial ⚠️
lightning/src/util/ser.rs	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3245      +/-   ##
==========================================
- Coverage   89.69%   89.69%   -0.01%     
==========================================
  Files         125      125              
  Lines      102794   102801       +7     
  Branches   102794   102801       +7     
==========================================
+ Hits        92206    92210       +4     
- Misses       7869     7874       +5     
+ Partials     2719     2717       -2     

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