Currently the `getnetworkinfo` returns something like: 

```
"localservices": "0000000000000449",
```

Manually parsing this consistently gives me a headache (see also https://github.com/sipa/bitcoin-seeder/pull/77).

It would be useful to parse this and show the right combination of `NODE_NETWORK`, `NODE_GETUTXO`, `NODE_BLOOM`, `NODE_WITNESS`, `NODE_NETWORK_LIMITED` and `NODE_COMPACT_FILTERS`. In addition the help text for `getnetworkinfo` could be expanded to mention the right BIP numbers for known flags.

There is some ad hoc parsing to populate e.g. `localrelay`, etc (?).  Their help text could also refer back to `NODE_GETUTXO`.

See also: https://en.bitcoin.it/wiki/Protocol_documentation#Network_address
: m_results{}
    {
    }
    RPCResults(RPCResult result)
        : m_results{{result}}
    {
    }
    RPCResults(std::initializer_list<RPCResult> results)
        : m_results{results}
    {
    }
    /**
     * Return the description string.
     */
    std::string ToDescriptionString() const;
};
struct RPCExamples {
    const std::string m_examples;
    explicit RPCExamples(
        std::string examples)
        : m_examples(std::move(examples))
    {
    }
    std::string ToDescriptionString() const;
};
class RPCHelpMan