dfdlx:trace function output not visible anywhere

The only way to debug expressions currently is by peppering them with calls to dfdlx:trace(expr, 'info string').

This would normally write "info string" then the value of the expr to stdout or something.

I couldn't find the output in any output tab or log tab in the vscode debugger. This should be console output from the daffodil parser.

To reproduce:

If you take the DFDLSchemas/CSV example, and add

`xmlns:dfdlx="http://www.ogf.org/dfdl/dfdl-1.0/extensions"
`
At the top of the csvHeaderEnforced.dfdl.xsd file, then wrap the dfdl:occursCount expression so it looks like:
`dfdl:occursCount="{ dfdlx:trace(fn:count(../../header/title), 'count: ') }"`
Then it should output a line of 'count: N' where N is the number of headers. That is once it gets to the item array.

I could not find the word "count" in any output tab.