dependencies: Migrate to ES module and organize dependencies

dependencies: Migrate to ES module and organize dependencies

gi modules are always loaded (there is no API for "set version without
loading"), so
we need to break dependencies.js into three sections:

- Required
- Compile-time optional
- Runtime optional

Required dependencies are always imported, compile-time optional
dependencies
are loaded if gnome-shell is compiled with support for them, and for
runtime optional dependencies we catch any errors when attempting to
load them.
If runtime optional dependencies fail to load we log a debug-level
message.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2822>