`banlist.dat` was introduced in https://github.com/bitcoin/bitcoin/pull/6310, storing nodes that were automatically banned (due to exceeding the misbehavior threshold) and manually banned (through the `setban` RPC).

Automatic bans were removed in https://github.com/bitcoin/bitcoin/pull/19219 and replaced with a discouragement filter. That filter is not saved to disk/persisted over shutdown/startup. The `banlist.dat` therefore now only contains addresses that have been banned through the `setban` rpc.

Since https://github.com/bitcoin/bitcoin/pull/15935, we have a specific file for configuration that is updated through the RPC and persisted over shutdown/startup, namely `settings.json`. We should therefore move the manual ban configuration from `banlist.dat` to `settings.json`. Doing so has a couple of benefits:

- `settings.json` is human readable and easily analyzable by any json parser.
- we wouldn't need to maintain custom [de]serialization code for the `banlist.dat` file.

`banlist.dat` is expected to be fairly small and infrequently updated, so disk space/performance are not huge concerns.
#include <interfaces/node.h>
#include <mapport.h>
#include <miner.h>
#include <net.h>
#include <net_permissions.h>
#include <net_processing.h>
#include <netbase.h>
#include <node/blockstorage.h>
#include <node/context.h>
#include <node/ui_interface.h>
#include <policy/feerate.h>
#include <policy/fees.h>
#include <policy/policy.h>
#include <policy/settings.h>
#include <protocol.h>
#include <rpc/blockchain.h>
#include <rpc/register.h>
#include <rpc/server.h>
#include <rpc/util.h>
#include <scheduler.h>
#include <script/sigcache.h>
#include <script/standard.h>
#include <shutdown.h>
#include <sync.h>
#include <timedata.h>
#include <torcontrol.h>
#include <txdb.h>
#include <txmempool.h>
#include <txorphanage.h>
#include <util/asmap.h>