chore: support setting DiscV5 and DNS-discovery in libwaku

[Ivansete-status]

Background

Epic: #2420

Details

This should be straightforward to achieve once the #2452 is completed. The basic idea is that the libwaku user should be able to set up DiscV5 and/or DNS-discovery the node managed by libwaku.

It is interesting to create an example where this can be tested. cwaku_example.c can serve as an inspiration.

[richard-ramos]

In go-waku bindings we had the following configuration items and functions available. Perhaps we could consider adding them to nwaku:

discv5: boolean, determine whether discv5 should be enabled or not
discV5BootstrapNodes: array of enrs
discV5UDPPort: int containing the udp port. Using 0 would automatically find an open port

dnsDiscoveryURLs: list of enrtrees. These would automatically be used as bootstrap nodes, and also added to the peerstore
dnsDiscoveryNameServer: list of nameservers to use to resolve the enrtree

extern char* waku_dns_discovery(char* url, char* nameserver, int timeoutMs)

Returns a list of multiaddress given a url to a DNS discoverable ENR tree

Parameters
    char* url: URL containing a discoverable ENR tree
    char* nameserver: The nameserver to resolve the ENR tree url. If NULL or empty, it will automatically use the default system dns.
    int timeoutMs: Timeout value in milliseconds to execute the call. If the function execution takes longer than this value, the execution will be canceled and an error returned. Use 0 for no timeout.

extern char* waku_discv5_update_bootnodes(char* bootnodes)

Update the bootnode list used for discovering new peers via DiscoveryV5

Parameters
    The bootnodes param should contain a JSON array containing the bootnode ENRs i.e. `["enr:...", "enr:..."]`