Optimize GStreamer plugin installation to reduce package size

Refactors GStreamer integration with platform-specific optimizations:

- Linux/Windows: Install only required plugins using explicit exclusion lists
- macOS: Preserve framework structure for codesigning (full framework copy)
- Android/iOS: Static linking with proper symbol visibility for JNI

Key changes:
- Add FindGStreamerQGC.cmake as entry point for GStreamer detection
- Add GStreamerConfig.cmake for shared configuration (URLs, exclusions)
- Rename _FindGStreamer*.cmake to standard FindGStreamer*.cmake naming
- Move iOS init template to cmake/find-modules/GStreamer/
- Add gstreamer_android-1.0.c.in template for Android
- Export JNI helper functions with proper visibility for androidmedia plugin
- Add graphene-1.0 explicit dependency for Windows (transitive dep issue)
- Remove unused meson.build from gstqml6gl

Author: HTRamsey

.github/build-config.json

@@ -4,7 +4,7 @@
   "android_min_sdk": "28",
   "android_platform": "35",
   "cmake_minimum_version": "3.25",
-  "gstreamer_android_version": "1.22.12",
+  "gstreamer_android_version": "1.28.0",
   "gstreamer_macos_version": "1.24.13",
   "gstreamer_minimum_version": "1.22.12",
   "gstreamer_version": "1.24.13",