feat: support name probing and conflict resolution

[keepsimple1]

This is to resolve issue #264 . The main changes are:

• Support probing as in RFC 6762 section 8.1 .
• Support Simultaneous Probe Tiebreaking as in RFC 6762 section 8.2
• Support conflict resolution as in RFC 6762 section 9 .

Public API changes:

• By default, name probing is enabled for publishing a service. Hence there will be around 1 second delay of successful service publishing.

• A new API ServiceInfo::set_requires_probe() to allow users to disable probing (at the service level) if they are sure there are no conflicts. This could be used if the service publisher does not want any delay due to probing.

• A new DaemonEvent::NameChange(DnsNameChange) is added to send notification about conflict resolution. DnsNameChange is like this:

#[derive(Clone, Debug)]
pub struct DnsNameChange {
    pub original: String,
    pub new_name: String,
    pub rr_type: u16,
    pub intf_name: String,
}

• Standard DNS resource record types are exported as RR_TYPE_A, etc. It makes it easier to check the value of DnsNameChange.rr_type.

Minimum Rust version changed from 1.63.0 to 1.65.0 to allow usage of let ... else statement.

The example code register.rs now requires to specify a hostname to allow easier testing conflict resolution.