[2.4.0] Checkmk Werk 16656 created: REST API: improve validation of host names

[//]: # (werk v2) # REST API: improve validation of host names key | value ---------- | --- date | 2024-03-26T09:56:52+00:00 version | 2.4.0b1 class | fix edition | cre component | rest-api level | 1 compatible | yes This werk improves upon the validation of host names in the REST API, so that it is in line with the GUI. In some cases the REST API will still be more restrictive, but invalid host names will no longer be allowed.