Change: add vcpkg.json to instruct vcpkg what dependencies we require

This works on all OSes, making it far simpler for any developer
to jump in. Just install vcpkg, run "vcpkg install" in our root,
and you have all the dependencies.

.github/workflows/release-linux.yml

@@ -132,28 +132,12 @@ jobs:
         # Make Python3 available for other packages. This needs to be done
         # first, as otherwise dependencies fail to build because Python3 is
         # not available.
-        /vcpkg/vcpkg install python3
-        ln -sf /vcpkg/installed/x64-linux/tools/python3/python3.[0-9][0-9] /usr/bin/python3
+        (
+          cd /
 
-        # SDL2 needs dbus, but dbus default install comes with libsystemd
-        # and some of libsystemd deps fail to build on our quite old linux.
-        # So just install basic dbus without any extra deps.
-        /vcpkg/vcpkg install dbus[core]
-
-        # Now we can install OpenTTD dependencies
-        /vcpkg/vcpkg install \
-          breakpad \
-          curl[http2] \
-          fontconfig \
-          freetype \
-          harfbuzz \
-          icu \
-          liblzma \
-          libpng \
-          lzo \
-          sdl2 \
-          zlib \
-          # EOF
+          /vcpkg/vcpkg install python3
+          ln -sf /vcpkg/installed/x64-linux/tools/python3/python3.[0-9][0-9] /usr/bin/python3
+        )
         echo "::endgroup::"
 
         echo "::group::Install breakpad dependencies"