In this commit, we move the serialisation details of a channel's
features to the DB layer and change the `models` field to instead use a
more useful `*lnwire.FeatureVector` type.
This makes the features easier to work with and moves the serialisation
to where it is actually used.
Define a new CachedEdgeInfo type and let the graph cache's AddChannel
use this. This will let us later on (for the SQL impl of the graph db)
only load from the DB what we actually need for the graph cache.
Update the GraphCache.UpdatePolicy method to take a
`models.CachedEdgePolicy` instead of a `models.ChannelEdgePolicy`.
Doing this will allow us later on to only fetch the necessary info for
populating the CachedEdgePolicy when we are populating the cache via
UpdatePolicy.
Here we add an explicit InboundFee field to the ChannelEdgePolicy
struct. Then, in the graph KVStore, at deserialisation time, we extract
the InboundFee from the ExtraOpaqueData. Currently we do this at higher
levels but we are going to move it to the DB layer so that when we add
the SQL implementation of the graph store, we can have explicit columns
for inbound fees. We need to account for the fact that we may have
invalid TLV already persisted though and we dont want to fail if we
deserialise those necessarily. So we return ErrParsingExtraTLVBytes now
if we fail to parse the extra bytes as TLV and then we let the callers
handle it similarly to how ErrParsingExtraTLVBytes is handled in that we
dont necessarily fail if we receive one of these errors.
As of this commit, we can now expect the InboundFee field of a
ChannelEdgePolicy to be set (if inbound fees are set on the policy) for
any update that we read from disk.
In preparation for an upcoming commit which will move all channel
funding tx validation to the gossiper, we first move the helper method
which helps build the expected funding transaction script based on the
fields in the channel announcement. We will still want this script later
on in the builder for updating the ChainView though, and so we pass this
field along with the ChannelEdgeInfo. With this change, we can remove
the TapscriptRoot field from the ChannelEdgeInfo since the only reason
it was there was so that the builder could reconstruct the full funding
script.
All the structs defined in the `channeldb/models` package are graph
related. So once we move all the graph CRUD code to the graph package,
it makes sense to have the schema structs there too. So this just moves
the `models` package over to `graph/db/models`.
