New function returns a list of (NAME . DESC) cons cells in the order
they were declared (in module packages.el files).
Fixes a load-order issue where autoloads from one package would depend
on the autoloads of another package, but was inserted into
doom-package-autoload-file *before* the depended package, causing
void-variable errors.
Also allows for a big refactor of the :plugins byte-compile target.