Replace using declaration with typedef

[musicinmybrain]

Fixes errors like:

[...]/progress_display.hpp:17:28: error: using-declaration for non-member at class scope
   17 |                 using std::uint64_t;
      |                            ^~~~~~~~

Additionally, name the typedef “uint64” instead of “uint64_t”, fixing errors like:

[...]/progress_display.hpp:31:30: error: 'uint64' has not been declared
   31 |                 void restart(uint64 expected_count)
      |                              ^~~~~~