This change tidies up a function signature to make use of records
that were created previously for use by other functions. They bundle
many common related values together to facilitate passing them around.

This change binds useLedgerPeers after unblocking due to a demand
for ledger peers by its clients. If this value has changed in the
configuration while the thread was dormant, ie. a race, it will be
picked up when the function unblocks.

Moved utility functions to ouroboros-network-api to support
calculating big ledger peer snapshots by upstream libraries,
for eg. Genesis consensus mode and bootstrapping a node with
a recent snapshot of these peers.

This change adds ToCBOR and FromCBOR instances that are necessary
to serialize a snapshot of ledger peers.

Depending on its topology configuration, a node may provide diffusion
layer with a snapshot of big ledger peers from some slot. This value
is provided as an argument when diffusion is initialized, and is
provided to ledgerPeersThread function, which contains the logic
when these peers, if any, can be provided to peer selection governor
when it requests them. This is especially useful when consensus is
ran in Genesis mode and when the node is bootstrapping so it may have
opportunity to connect to these trustworthy peers when they may not
be yet available on its own ledger.

encoding, as well as checking that ToCBOR and FromCBOR are working
together correctly.

Improved naming of functions related to calculating big ledger stake
distribution which were to moved public ouroboros-network-api component.