`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.
#ifndef BITCOIN_ADDRDB_H
#define BITCOIN_ADDRDB_H
#include <fs.h>
#include <net_types.h> 
#include <serialize.h>
#include <string>
#include <vector>
class CAddress;
class CAddrMan;
class CDataStream;
class CBanEntry
{
public:
    static const int CURRENT_VERSION=1;
    int nVersion;
    int64_t nCreateTime;
    int64_t nBanUntil;
    CBanEntry()
    {
        SetNull();
    }
    explicit CBanEntry(int64_t nCreateTimeIn)