In the previous commit the AdditionalEdge interface was introduced
with both of its implementations `BlindedEdge` and `PrivateEdge`.
In both cases where we append a route either by a blinded route
section or private route hints we now use these new types. In
addition the `PayloadSizeFunc` type is introduced in the
`unifiedEdge` struct. This is necessary to have the payload size
function at hand when searching for a route hence not overshooting
the max sphinx package size of 1300 bytes.
We rename `ChanUpdateOptionMaxHtlc` to `ChanUpdateRequiredMaxHtlc`
as with the latest changes it is now required.
Similarly, rename `validateOptionalFields` to
`ValidateChannelUpdateFields`, export it to use it in a later commit.
This commit adds the maximal capacity between two nodes to the unified
edge data. We use MaxHTLC as a replacement if the channel capacity is
not available.
In tests we use larger maxHTLC values to be able to convert to a
non-zero sat capacity.
This commit refactors the semantics of unified policies to unified
edges. The main changes are the following renamings:
* unifiedPolicies -> nodeEdgeUnifier
* unifiedPolicy -> edgeUnifier
* unifiedPolicyEdge -> unifiedEdge
Comments and shortened variable names are changed to reflect the new
semantics.