XML representation not working

Hi,

There appears to be an issue when XML is set as representation and expected as output. This should probably be a PR instead of an issue, but here is explanation of the issue.

Minimal example:

```
const queryDef = {
schema: "nms:recipient",
operation: "select",
select: { node: [{ expr: "@id" }, { expr: "@email" }] },
lineCount: 50,
};

const query = client.NLWS.xml.xtkQueryDef.create(queryDef) // or xml set globally, same result
const result = await query.executeQuery()
```
Above throws error:
```
Error: TypeError: xmlRoot.hasAttribute is not a function
at Client._writeSoapCallParameters ([...]\@adobe\acc-js-sdk\src\client.js:1334:38)
```

Issue seems to be in @adobe\acc-js-sdk\src\client.js:1319 - function _writeSoapCallParameters:
```
var xmlValue = this._fromRepresentation(docName, paramValue, paramRepresentation || representation);
```
Issue is that at this point representation is SimpleJson. _fromRepresentation with 'xml' as representation always return paramValue without changes. If we instead convert to xml from SimpleJson the subsequent hasAttribute and rest of code works:

```
var xmlValue = this._convertToRepresentation(paramValue, "SimpleJson", paramRepresentation || representation);
```

Regards,
Jonas

Read src/client.js around _writeSoapCallParameters at lines 1319-1334 and reproduce the minimal XML query example from the issue. Trace how the representation is selected before hasAttribute is called. Done means the XML-configured query executes without the TypeError and the existing representation behavior remains intact.

Written by the indexing model from the issue text.