Test release SDL2 clients

A working SDL2 client

- Increased vesion to 4.9.3.0.1.1.
- Add USE_SDL2 macros thorough the code.
- Add OS_SUB_SDL2 and OS_SUB_GCU_SDL2 and use it in VERSION_OS_SUB.
- Add Unified makefile.sdl2 for linux compiling and windows cross compiling.
  - Compile windows sdl2 client without wine and tolua.exe
  - Remove unnecessary generation rules for common/z_pack
  - Refactor the tolua file generation
  - Make tomenet and tomenet.exe executables in one run in SDL2 client
  - add automatic header-dependency tracking with -MMD/-MP
- Update .gitignore
- Introducing SDL2_GAME_PATH, SDL2_USER_PATH and SDL2_PATH_SEP variables.
- Introduce SDL2 user directory
  - Declare and expose new ANGBAND_USER_DIR* pointers based on ANGBAND_DIR*
  - Inform about creating user directories, refactor
  - Copy default scripts into `ANGBAND_USER_DIR_SCPT` when it's created
  - Redirect SDL2 client file I/O to the SDL2 user directory
  - Store temporary files and logs in the SDL2 temp folder
  - Rename copy_file to my_fcopy.
  - Edit my_fopen to open files with fallback and use instead of fopen in SDL2 client
  - Prefer user dir for fonts/tilesets/macros; install audio packs to user xtra
  - Use user dir when saving sound/music.cfg files
  - Override the user storage dir via TOMENET_SDL2_USER_PATH environment variable
- Using a dir in sdl2 user path as tmpdir when no env value is set.
- Add common/net-sdl2.c using the SDL2 SDL_net library and use it with sdl2 clients.
- Add main-sdl2.c based on main-x11.c and use it in SDL2 client.
- Add multi-layer multi-masks tiles support.
- Add tile cache support, but turn it off (not needed, it is fast).
- Graphic tiles are initialized after pref file is loaded.
- Graphics pref file now contains information about masks colors.
- Per-subtileset mask colors are now loaded from .prf files and used.
- Support PCF and TTF fonts in the SDL2 fonts menu, handle PCF fonts as graphical
  - Add pcf fonts to lib/xtra/font for sdl2 clients
- Add window decorations toggle to settings file and in-game window flags menu
  - On window move, store coordinates considering decorations.
  - Windows are created with decorations by default.
- Using tomenet.cfg in sdl2 user path as config (based on .tomenetrc).
- Make check_guide_checksums work for sdl2 with curl & ssl.
- Removing goto from client/client.c in mangrc read function.
- Use SDL2_image library for screenshots, but it is optional.
  - If not using SDL2_image, save screenshots to BMP instead of PNG.
- Add SDL2_STICKY_KEYS macro and disable by default
- Create snd-sdl2.c file based on snd-sdl.c
  - switch SDL2 client sound to SDL2
  - allow sound code to compile with either `SOUND_SDL` or `SOUND_SDL2`
  - fix sdl2 quit on music quit, add debug logs to sdl2 unarchive
  - guard SDL mixer shutdown
  - determine fd availability by opening null files on init
  - fix SDL2 audio FD accounting for samples vs music
  - fix wrong mutex unlock when loading music (also in snd-sdl.c)
  - refactor sound_sdl_init function
  - fix audio init failure cleanup
  - Add subset logic
  - Fix jukebox autoplay finish and destuctive pack-switch
  - Fix post-autoplay cursor restore
  - Ix autoplay stop after first song after a/u/e session
  - Stabilize jukebox restore/fadeout/shutdown state across mixer reloads and previews
  - Preserve force-disabled and runtime-disabled SDL2 audio state correctly in config and toggles
  - Ignore transient EMFILE/ENFILE when loading audio events
- Add libarchive-based unzipping sound/music pack 7zipped files.
  - detect libarchive in makefile.sdl2 via pkg-config and link when available
  - Notify when unpacking unsupprted 7z encrypted archive
  - More archives support in sdl2 clients (.zip, .tar, .tar.gz).
- Use SDL_OpenURL for file and link opening
- Hide disable_tile_cache into TILE_CACHE_SIZE ifdef macro
- Fix double separator in lua scripts.
- Using semi-transparent black as top tile outline color for UG_2MASK mode
- Graphics tiles outline layer generation for fg/bg tiles when UG_2MASK
  mode. Option to force outline generation of specific width.
- Graphics tiles preferences on-the-fly change and
  tiles with layers preview in in-game graphics menu.
- Graphic subtiles implemenation. Respects subtiles in preview an cache.
- Graphics cache resets subset/index during init and teardown to keep entries clean before reuse.
- Loading graphics images of tiles and subtiles from user location first
- Add tileset resize modes support, default is NEAREST.
- Treating the SDL2 Delete key separately from Backspace so prompts
  receive '\177' (0x7F), while keeping the Backspace handling unchanged.
- In knowledge menu, open last screenshot instead of conversion
  - Open user folders in in-game knowledge menu too.
- Make macroset scan OS independent for SDL2 test clients
- Add basic player sounds according to sound.cfg.default content.
- Create fake but deterministic MAC depending on PC stats
- Add .prf files to lib/user for sdl2 clients
- Get rid of most compiler warnings.
- Build sdl2 linux client to prefer .so beside the binary.
- Make SDL2 ip_iface return IPv4 string like Windows client.
- Add optional GCU support for SDL2 Linux client build, default is off
- Added build scripts for fedora 41 & 43 distrobox build containers.
- Added CI for github with Fedora 41 build image and compile-check workflow
- Added CI for building client/server release archives on tag push and
  append them if release is made.
- Updated guide with info about sdl2 clients how to build them
- Startup logo is graphic only when all used solid tiles are loaded
- Add mask color documentation for sdl2 clients tileset bitmap