LibGfx: Implement image decoder for TinyVG (.tvg)

This adds a decoder for the TinyVG vector format (https://tinyvg.tech/).
TinyVG is a very simple binary vector format, but it is good enough to
represent a lot of SVGs, without needing the full web engine.

The main use case for Serenity is for scalable icons (which .tvg easily
handles).

Userland/Libraries/LibGfx/CMakeLists.txt

@@ -49,6 +49,7 @@ set(SOURCES
     ImageFormats/QOILoader.cpp
     ImageFormats/QOIWriter.cpp
     ImageFormats/TGALoader.cpp
+    ImageFormats/TinyVGLoader.cpp
     ImageFormats/WebPLoader.cpp
     ImageFormats/WebPLoaderLossless.cpp
     ImageFormats/WebPLoaderLossy.cpp