Reformat the XQuery code so it is consistent and readable

[adamretter]

@chakl it's all formatting apart from two small things:

1. Adding some missing return types to one or two functions.

2. Simplifying element construction in maybe one or two places.

I think the changes are very minor. I'm sorry you feel it's too big. Does the above explanation help you, or do you still need it broken into 3 commits?

[chakl]

do you still need it broken into 3 commits?

Yes, please do.

• make a separate commit for the changes to function signatures. Enforcing signatures might affect existing poorly written controllers, so that could break things, and applications need to be re-tested. Other than that, I'm fully with you about explicit function signatures.
• make a separate commit for the changes that replace XQuery element construction with inline XML. I did not follow through the original long PR, but I wonder why you suggest these changes? These should be behaviorally identical, so what's the gain of changing representation X to representation Y?
• the remainder should only contain functionally irrelevant whitespace changes or minor typo fixes.

[adamretter]

@chakl As requested, I have now broken this down into a number of smaller atomic commits. Could you take another look please?