[FEAT] Configure a client without a port

[legzo]

Describe the enhancement

I would like to be able to specify a connection URL without a port.

Why is this needed?

My ES cluster has a proxy in front of it and the API responds when no port is specified but does not responds if I specify 80 as port. So, right now, I can't use kt-search at all (unless I missed something in the docs, but I checked the code and it seems that port is non nullable in Node so....)

Will you be able to help with a pull request?

I sure can. Maybe it is possible to just make port nullable in Node data class, but it may have implications that I don't suspect... :)

Cheers

[jillesvangurp]

Good suggestion. Doing a quick fix for this.