Replaced use of `flags_test_assets_dir` with `BKE_tempdir_case()`.
Use `BLI_path_move` to handle moving file across filesystems where `BLI_rename` would fail.
Set dir parameter to const for BLI_change_working_dir.
Added non-ASCII characters to the test directory.
Mac and Linux fixes. Linux now sets PWD when using BLI_change_working_dir. Mac uses NSFileManager through some new Mac-only wrapper functions.
Changed temporary directory to use a directory in the flags_test_asset_dir.
Ensure that operation to change working directory is from the main thread.
Removed `is_usdz_export` flag to now check if `usdz_filepath` is set instead.
Renamed `unarchived_filepath` to clearly distiguish from `usdz_filepath`. Added comments to clarify the difference.
Created a method on `ExportJobData` to return the final export filepath.
Added comment summary to `perform_usdz_conversion` describing functionality.