contractcourt: add HtlcBlobs to taprootBriefcase

In this commit, we add the set of HtlcBlobs to the taprootBriefcase
struct. This new field will store all the resolution blobs for a given
HTLC. We also add some new property based tests along the way for
adequate test coverage.

go.mod

@@ -64,6 +64,7 @@ require (
 	google.golang.org/protobuf v1.33.0
 	gopkg.in/macaroon-bakery.v2 v2.0.1
 	gopkg.in/macaroon.v2 v2.0.0
+	pgregory.net/rapid v1.1.0
 )
 
 require (