fix: handle directories, references, and unnecessary files

[crowecawcaw]

What was the problem/requirement? (What/Why)

There were several related bugs with automatically detecting and attaching files:

• Bug: folders are sometimes being included as input files instead of directories #124
• Bug: directories are skipped when determining assets to upload #126
• Bug: parse scene files includes possibly unnecessary files #122

What was the solution? (How)

When detecting if a parameter is a path or file, evaluate the parameter first to resolve the references and attach the expanded path. Also ignore op: data references which are not files.

What is the impact of this change?

Directories are detected. References in file and directory names are handled correctly. Data references are ignored.

How was this change tested?

Expanded unit tests. For manual testing, I created a file cache inside a geometry node and pointed the file cache to directories both with $HIP as part of the path and without it. I then opened the Deadline Cloud node and clicked "Parse files". The files and directories were correctly detected and attached.

Was this change documented?

No documentation needed.

Is this a breaking change?

No

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[lucaseck]

Thank you for the contributions. I've left some minor comments.

As well, for #122 this won't fully fix it since I don't see anything about those header files being ignored. If that's going to be a separate PR no worries. Just didn't want to have the issue be closed without all parts being fixed.