Android: decouple video/audio subsystems from JNI initialization

Allow Android embedders to use SDL without the full video/audio Java
layer by gating subsystem-specific code behind SDL_VIDEO_DISABLED and
SDL_AUDIO_DISABLED preprocessor flags.

This enables applications that only need joystick/gamepad support
(e.g. Qt-based apps like QGroundControl) to build SDL without shipping
stub Java classes for unused subsystems.

Changes:
- Split SDLActivity JNI method table into core (lifecycle, hints,
  permissions) and video (surface, input, clipboard, orientation)
- Gate SDLAudioManager and SDLInputConnection JNI registration
- Make checkJNIReady() subsystem-aware: no longer requires
  mAudioManagerClass when SDL_AUDIO_DISABLED
- Group method ID resolution by subsystem in nativeSetupJNI()
- Guard all video/audio function implementations and declarations
- Keep display orientation accessors always available (needed by camera)
- Add subsystem-selective SDL.setupJNI(int)/initialize(int) to SDL.java
  with backwards-compatible zero-arg overloads
- Guard SDL_VIDEO_DRIVER_ANDROID and related defines in
  SDL_build_config_android.h

build-scripts/check_android_jni.py

@@ -82,6 +82,8 @@ def collect_jni_bindings_from_c() -> dict[str, set[JniMethodBinding]]:
                     if re.match(r"\};", line):
                         in_struct = False
                         break
+                    if re.match(r"\s*(#|//)", line):
+                        continue
                     n = re.match(r"""\s*\{\s*"(?P<method>[a-zA-Z0-9_]+)"\s*,\s*"(?P<spec>[()A-Za-z0-9_/;[]+)"\s*,\s*(\(void\*\))?(HID|SDL)[_A-Z]*_JAVA_[_A-Z]*INTERFACE[_A-Z]*\((?P=method)\)\s*\},?""", line)
                     assert n, f"'{line}' does not match regex"
                     methods.add(JniMethodBinding(name=n["method"], spec=n["spec"]))