Add new packages and build scripts for various libraries

- Added Nuklear GUI library with build script and configuration.
- Introduced OpenH264 encoder/decoder with build configuration.
- Added PortAudio library for audio I/O with custom build script.
- Included Python Execnet for multi-Python deployment.
- Added Pytest Xdist plugin for distributed testing.
- Introduced Shaderc for shader compilation tools.
- Added Snappy compression library with necessary patches and configuration.
- Included SoundTouch audio processing library with build configuration.
- Added SRT library for secure reliable transport.
- Introduced VapourSynth video processing framework with configuration.
- Added Vid.stab for video stabilization.
- Included WebRTC Audio Processing library with build configuration.
- Added X264 video encoding library with patches for POSIX compliance.
- Introduced X265 video encoder with build configuration.
- Added XKeyboard Config for X keyboard configuration files.
- Included Xorg XKBComp for keyboard description compilation.
- Added Xvidcore MPEG-4 video codec library with configuration.
- Introduced ZeroMQ messaging system with patches and build configuration.
- Added Zimg library for scaling and colorspace conversion.

extra/libssh/libssh.toml

@@ -0,0 +1,40 @@
+[build]
+type = "cmake"
+
+[build.flags]
+build_dir = "build"
+configure = [
+    "-DWITH_GSSAPI=OFF",
+    "-G Ninja",
+    "-DUNIT_TESTING=OFF",
+]
+split-docs = true
+post_compile = [ "cmake --build build --target docs" ]
+post_install = [ "mkdir -p $DESTDIR/usr/share/doc/libssh", "cp -r build/doc/html $DESTDIR/usr/share/doc/libssh" ]
+
+[dependencies]
+build = [
+    "cmake",
+    "cmocka",
+    "doxygen",
+    "openssh",
+    "python",
+    "ninja"
+]
+runtime = [
+    "glibc",
+    "openssl",
+    "zlib-ng",
+]
+
+[package]
+description = "Library for accessing ssh client services through C libraries"
+homepage = "https://www.libssh.org/"
+license = "LGPL-2.1-or-later"
+name = "libssh"
+version = "0.12.0"
+
+[[source]]
+extract_dir = "$name-$version"
+sha256 = "1a6af424d8327e5eedef4e5fe7f5b924226dd617ac9f3de80f217d82a36a7121"
+url = "https://www.libssh.org/files/0.12/libssh-$version.tar.xz"