Allow paying to blinded routes

[thomash-acinq]

Replaces #2429
Adds BlindedHop in addition to the existing ChannelHop and NodeHop.
Bolt12 invoices encode the blinded routes as extra edges.

[codecov-commenter]

Codecov Report

Merging #2467 (4c2e415) into master (3b12475) will decrease coverage by 0.15%.
The diff coverage is 84.19%.

@@            Coverage Diff             @@
##           master    #2467      +/-   ##
==========================================
- Coverage   84.92%   84.76%   -0.16%     
==========================================
  Files         198      198              
  Lines       15783    15883     +100     
  Branches      637      672      +35     
==========================================
+ Hits        13404    13464      +60     
- Misses       2379     2419      +40     

Impacted Files	Coverage Δ
...in/scala/fr/acinq/eclair/channel/ChannelData.scala	98.11% <ø> (ø)
.../main/scala/fr/acinq/eclair/db/DualDatabases.scala	11.27% <0.00%> (+0.32%)	⬆️
.../src/main/scala/fr/acinq/eclair/db/NetworkDb.scala	100.00% <ø> (ø)
...src/main/scala/fr/acinq/eclair/db/PaymentsDb.scala	82.50% <0.00%> (-2.12%)	⬇️
...n/scala/fr/acinq/eclair/json/JsonSerializers.scala	95.12% <ø> (ø)
...scala/fr/acinq/eclair/router/BalanceEstimate.scala	98.91% <ø> (-1.09%)	⬇️
.../eclair/wire/protocol/LightningMessageCodecs.scala	100.00% <ø> (ø)
...ala/fr/acinq/eclair/wire/protocol/OfferTypes.scala	94.53% <0.00%> (-0.75%)	⬇️
.../fr/acinq/eclair/wire/protocol/RouteBlinding.scala	95.23% <ø> (ø)
.../scala/fr/acinq/eclair/payment/PaymentPacket.scala	62.38% <57.69%> (-6.37%)	⬇️
... and 38 more

[t-bast]

Replaced by #2482