Have PySide2 fixhdr display 'Please Wait' windows and progress counters

OS: Fedora 36

Tracedb size: 19 GB in 8556 files

Observed behavior: There is not a 'Modifying Headers, Please wait' window that automatically pops up or modifying trace progress count at the bottom of the main fixhdr window. (These features exist in previous versions of fixhdr). The program produces a 'not responding' message from the OS when modifying all traces in the test tracedb set. It does complete the process successfully and list a count of files with headers modified at the bottom of the screen.

Requested behavior: Restore the 'Modifying Headers, Please wait' window and modifying trace progress. This will improve the user experience, reduce confusion, and make it consistent with previous versions of fixhdr.

Other: the tracedb build is extremely fast on the test machine so I can't tell if there is a 'Building trace db, please wait' window that pops up or trace db progress count at the bottom of the main fixhdr window. If there is not, can those be restored as well? If this is unknown, please let me know and I will use a larger test dataset for fixhdr and other PASSOFT applications that build a trace db.