Multithreaded file content search

[Ziyan]

I'm heavily CPU limited when searching for file contents in the 'Find Files' dialog, especially when the 'Search archives' option is enabled.
I frequently use this feature when searching in hundreds of compressed log files, and my disk usage (according to Task Manager) is usually around 5-10% in such cases, with one CPU thread maxed out (this was tested on a Ryzen 9 3900X machine with a Samsung 970 EVO SSD).

It would be nice if Total Commander could divide the work across several threads when searching file contents (different threads could search in different files). It would vastly speed up search operations on multicore systems with fast SSDs (in my example use case, it could be more than 10 times faster).