Added configurable pak shortcut in game menu

[bmpriest]

What

• Adds a setting to set a certain pak as launchable from the in-game menu.
  • Only paks with "in_game_shortcut": true are considered valid for assignment; feature is opt-in for pak makers.
  • Paks can also set a "short_name" value for display comfort. Otherwise it limits it to 12 characters.
• Pak is launched from the in-game menu with the 'X' button.
• Closing the pak returns to the menu (and game)
• Passes along two environmental variables: rom path and emu pak, to allow for context aware paks

Why

• Ideally, to allow for "guide" paks that can be referenced while still in-game. Quitting to navigate to a Tool pak, looking up whatever you need, quitting and then navigating back to the game is a complicated flow. We can simplify this by including a way to launch the .pak from the game menu
• Could also allow for Pokedex paks, or Netplay paks, or (later) even perhaps a way to listen to your own music while playing a game, or any reason you might want to look at something in-game without losing your spot.
• I tried to focus on something that would be easy to maintain, allowing pak launching under only certain conditions.

How

• ma_menu.c: duplicates much of the functionality of the L3/R3 function pak shortcut. If unbound, displays the current ( ( POWER ) SLEEP ) button hint; if bound to a pak, truncates the name to 12 characters if too long, or uses the short_name attribute. Bound to "X."
  • Keeps the underlying emulation paused and launches the pak on a fork().
  • Quitting/leaving the pak returns directly to the menu.
• fnbuttonmenu.cpp/fnbuttonmenu.h: re-uses a good bit of the code to build a list of valid paks
• settings.cpp: adds the buildPakShortcutItem() under "In-Game"
• utils.c/utils.h: allows determination of in_game_shortcut flag, as well as getting the name or short_name from pak.json
• config.c/config.h: allows the saving of the setting to a pakshortcut.txt file. CFG_init() and CFG_sync() can remove entries from minuisettings.txt, so this is admittedly a small workaround.

Proof of Concept:

GameGuide.pak.zip

GameGuide.pak is a very basic text file reader that, if launched from in-game, looks for a .txt file under:

1. <ROM folder>/.media/<ROM filename stem>.txt
2. <ROM folder>/<ROM filename stem>.txt
3. /Guides/<emulator tag>/<ROM filename stem>.txt
4. /Guides/<ROM filename stem>.txt

and launches it automatically, as well as remembering the user's place in the file. Can also be launched from Tools with a SD Card file browser.

Screenshots: