osw_config_keys: add stdexcept libraries

[RuffaloLavoisier]

• error: 'invalid_argument' is not a member of 'std'

  In file included from include/osw_hal.h:17:0,
               from include/./apps/_experiments/autumn.h:4,
               from src/apps/_experiments/autumn.cpp:2:
  include/osw_config_keys.h: In static member function 'static size_t OswConfigKeyDropDown::getOptionIndex(const std::vector<const char*>&, const String&)':
  include/osw_config_keys.h:245:15: error: 'invalid_argument' is not a member of 'std'
       throw std::invalid_argument("Option not found in options list");
             ^
  include/osw_config_keys.h: In member function 'void OswConfigKeyDropDown::checkValidOption(const String&)':
  include/osw_config_keys.h:266:15: error: 'invalid_argument' is not a member of 'std'
       throw std::invalid_argument("Invalid option value for dropdown key!");
             ^
  In file included from include/osw_hal.h:17:0,
               from include/./apps/_experiments/dnatilt.h:4,
               from src/apps/_experiments/dnatilt.cpp:2:
  include/osw_config_keys.h: In static member function 'static size_t OswConfigKeyDropDown::getOptionIndex(const std::vector<const char*>&, const String&)':
  include/osw_config_keys.h:245:15: error: 'invalid_argument' is not a member of 'std'
       throw std::invalid_argument("Option not found in options list");
             ^
  include/osw_config_keys.h: In member function 'void OswConfigKeyDropDown::checkValidOption(const String&)':
  include/osw_config_keys.h:266:15: error: 'invalid_argument' is not a member of 'std'
       throw std::invalid_argument("Invalid option value for dropdown key!");

[simonmicro]

LGTM