feat: serialized XML omit default namespaceID

[jkowalleck]

remove the XML-namespace and convert it to noNS/defaultNS by omiting the nsID

current serialization result:

<?xml version="1.0" encoding="UTF-8"?>
<ns1:bom xmlns:ns1="http://cyclonedx.org/schema/bom/1.4" ...>
</ns1:bom>

should be

<?xml version="1.0" ?>
<bom xmlns="http://cyclonedx.org/schema/bom/1.4" ...>
</bom>

[jkowalleck]

This is actually a change in the serialization result, even though it is not a qualitative change.

but shill, this is a breaking change

[jkowalleck]

for technical reasons, this is pretty hard.

first of, the serializer does not add namespaces to XML-attributes, so setting a defaultNS did not work.
registereing the NS as identifier '' did the trick for serialization.

but then the deserialization happened.
and this one was completely unavle to detect the defaultNS, and assumed it was '' -- which is the identifier for the defaultNS not the defaultNS itself ...
and then the nameSpace-detection on XML-attributes fails ...

ow maaaan .....

---

caused

• bug: serialization with defaultNS fails madpah/serializable#12
• bug: defaultNamespace detection fails on XML-attributes when deserializing madpah/serializable#11

[jkowalleck]

closed via #458