The key functions added are:
`bool enableForwarder(const String &domainName=emptyString, const IPAddress &dns=uint32_t)0)`
If specified, `enableForwarder` will update the `domainName` that is used to match DNS request to this AP's IP Address. A non-matching request will be forwarded to the DNS server specified by `dns`.
Returns `true` on success.
Returns `false`,
* when forwarding `dns` is not set, or
* unable to allocate resources for managing the DNS forward function.
`void disableForwarder(const String &domainName=emptyString, bool freeResources=false)`
`disableForwarder` will stop forwarding DNS requests. If specified, updates the `domainName` that is matched for returning this AP's IP Address.
Optionally, resources used for the DNS forward function can be freed.
