osx-framework.recipe: Dynamically generate the list of libraries and ship pkg-config

Instead of using a very very outdated hard-coded list, dynamically generate the list of libraries and exclude gstreamer libraries we don't want, like gst-editing-services or rtsp-server

Fixes #210 (closed)

Also contains:

osx-framework.recipe: Also install pkg-config binary
Some projects, for example the GStreamer Rust bindings, need to use
pkg-config instead of the generated framework. Provide pkg-config so
that people don't have to install Homebrew or something for it.

Closes https://gitlab.freedesktop.org/gstreamer/cerbero/issues/209