chore(fixes): Unwrap yaml before converting and fix volume name variable

2 fixes:

- the first problem to resolve is that some volume names can have "-" in
the name. We now replace them by "_"
- the second problem is that k8s.io library truncates the lines and so
we cannot split the files by lines. We now "unwrap" the result.

TODO: globalize the `yaml.Marshal()` code to our own specific function

generator/values.go

@@ -92,6 +92,7 @@ func (v *Value) AddIngress(host, path string) {
 
 // AddPersistence adds persistence configuration to the Value.
 func (v *Value) AddPersistence(volumeName string) {
+	volumeName = strings.ReplaceAll(volumeName, "-", "_")
 	if v.Persistence == nil {
 		v.Persistence = make(map[string]*PersistenceValue, 0)
 	}