ddns-scripts: add PROVIDES for old package names

ddns-scripts: add PROVIDES for old package names

* ddns-scripts-services: provide ddns-scripts_service
* ddns-scripts-cloudflare: provide ddns-scripts_digitalocean.com-v2
* ddns-scripts-freedns: provide ddns-scripts_freedns_42_pl
* ddns-scripts-godaddy: provide ddns-scripts_godaddy.com-v1
* ddns-scripts-noip: provide ddns-scripts_no-ip_com
* ddns-scripts-nsupdate: provide ddns-scripts_nsupdate
* ddns-scripts-route53: provide ddns-scripts_route53-v1
* ddns-scripts-cnkuai: provide ddns-scripts_cnkuai_cn

https://github.com/openwrt/packages/pull/13509 renamed many ddns-scripts
packages, but didn't include a PROVIDES for the old package names to
make updates work well.

Signed-off-by: Michal Vasilek <michal.vasilek@nic.cz>