Template read_from_json_string

[ymber]

Summary

SUMMARY: Infrastructure "Template read_from_json_string"

Purpose of change

I want to use read_from_json_string for a load of different quantity strings and this is more efficient than an overload for each unit type. See #31079.

Describe the solution

Use templates for read_from_json_string and move unit value vectors to appropriate classes.

Describe alternatives you've considered

Overloads for every unit type.

[ZhilkinSerg]

I guess some tests code using read_from_json_string need to be updated now:

time_duration_test.cpp: In function 'time_duration parse_time_duration(const string&)':
time_duration_test.cpp:12:27: error: 'read_from_json_string' is not a member of 'time_duration'
     return time_duration::read_from_json_string( jsin );
                           ^~~~~~~~~~~~~~~~~~~~~
make[1]: *** [Makefile:45: objwin/tiles/time_duration_test.o] Error 1