Fix playing generic game not spending battery charges

[MilosRasic]

Summary

SUMMARY: Bugfixes "Fix playing generic game not spending battery charges"

Purpose of change

Handheld game system is not spending battery charges when a generic game is played. Looking at the code in activity_handlers.cpp, activity_handlers::game_do_turn() has battery code but it's completely lacking in activity_handlers::generic_game_do_turn().

Thought I'd fix it because I'm playing games to pass time while listening to music to boost my focus while learning from books 😃

Describe the solution

Generic game handling code is extracted as

void generic_game_turn_handler( player_activity *act, player *p, int morale_bonus,
                                int morale_max_bonus );

then both activity_handlers::generic_game_do_turn() and activity_handlers::game_do_turn() call it with different morale arguments. Values remain the same as before the fix.

Also had to add activity target in iuse::portable_game() because it was skipped by an early return when playing a generic game.

Describe alternatives you've considered

At first I thought I'd have activity_handlers::generic_game_do_turn() take additional parameters morale_bonus and morale_max_bonus with default values, then call it from activity_handlers::game_do_turn(), but it turns out real activity handlers called directly to handle an activity must have a specific signature, so I opted to extract the common logic as a separate function instead.

Testing

Loading my save with a handheld game system at the ready and tested following scenarios:

• play a specific minigame a bit, then press q to quit
• play a generic game
• repeat both of the above when running out of battery in the middle of the activity

Ran unit tests. Looks like activity handlers are not covered. There's a spelling failure unrelated to my changes.