To avoid "forked" types creeping into `BlobSidecar`, move the reduction
to `BlobSidecarInfoObject` to the sole caller. The info object is fork
agnostic, so does not need "forked" if `BlobSidecar` ever updates.
Use the same eviction policy for blocks as already the case for blobs.
FIFO makes more sense, because it favors keeping ancestors of blocks
which need to be applied to the DAG before their children get eligible.
Blobs are cached from gossip and other sources for all orphans, not just
those specifically tagged as `blobless`. `blobless` only means that they
are actively fetched from the network. The `MaxBlobs` should be aligned
to match `MaxOrphans`. Note that blobs are tiny compared to blocks, so
this isn't a huge memory hog.
`v1.4.0-beta.4` made the Gossip rules more strict and now requires to
ignore blobs from other branches if there are equivocating blocks.
Those blobs are only requestable via Req/Resp.