`devShell` accepted either a package def, a submodule value, or a
function to a submodule value. `devShells` only accepted package defs.
This brings all the options of `devShells` to any devShell configured
with `devShells`.
Before, devShell could be set to a submodule config, a package def, or a
function taking module args and returning a submodule config. This
changes the last form to take the package set instead.
This enables cleaner configuration by not needing each option to
individually be a function of pkgs. Passing pkgs also gives more
flexibility as all the module args are available under the `moduleArgs`
attr.
Code that relied on module args not directly in the package set will now
have to access them from the `moduleArgs` attr.
If a package depends on a package with same name, this causes an
infinite recursion as it tries to depend on itself. This is not likely
what was intended, and breaks ability to re-export packages, so instead
if a package depends on the same name, that now refers to the previous
version.
Instead of having to call the configuration generation functions, the
params can just be set, and the functions will be called automatically
with additional useful settings automatically set.
The `propagationModule` config option provides a module that can be used
to propagate flakelight configuration into other module systems such as
NixOS or home-manager.
The set of args passed to modules is useful for more than just
autoloading. This renames it appropriately and makes it available
through pkgs arguments as well.
The formatter uses `devShell.packages` for its path which is not
available when devShell is null. A default value of empty list should be
used when devShell is null.
Using a submodule for devShell removes the need to make every option
nullable and the need to check all of them. By using nullOr submodule,
we can tell if the value has been set and have default values for
options.
This also enables enabling a devShell with no options set.
