Function coerceNodeId

Convert a value into a nodeId:

@description:

• if nodeId is a string of form : "i=1234" => nodeId({value=1234, identifierType: NodeIdType.NUMERIC})
• if nodeId is a string of form : "s=foo" => nodeId({value="foo", identifierType: NodeIdType.STRING})
• if nodeId is a string of form : "b=ABCD=" => nodeId({value=decodeBase64("ABCD="), identifierType: NodeIdType.BYTESTRING})
• if nodeId is a NodeId : coerceNodeId returns value