Improve labels value check

[tuxtof]

/kind feature

Describe the solution you'd like

CCM creates labels (like topology) based on prism information like categories or PC/PE name; if the value doesn't respect the correct syntax, CCM reconciliation fails in a loop, the node is never initialized, and CCM continues to run forever, letting the cluster not ready.

Valid label value are:

• must be 63 characters or less (can be empty),
• unless empty, must begin and end with an alphanumeric character ([a-z0-9A-Z]),
• could contain dashes (-), underscores (_), dots (.), and alphanumerics between.