Multithreading support

[CebFu]

@shwina
I have installed pyamgx on Windows system succefully, and tested a large symmetric sparse linear system, it works well. It is said in the document that pyamgx only supports “simple” resources objects for single threaded, single GPU applications. Is it possible to implement a multithreaded version such as to make it more competitive. In addition, the function cfg.create_from_dict( ) seems not to be working properly (cfg.creat( ) and cfg.creat_from_file( ) are both Ok). Thanks for your contributions.

Best wishes