Simplify imports

[planktonic]

Right now we there are only two options when importing bitstyles in a project (ignoring the legacy @import):

• @use each module individually
• @use all of bitstyles

A middle ground would be great — perhaps adding an index file (index.scss) to each layer to allow importing of all atoms, all molecules, all utilities each in one go? Something like:

@use "~bitstyles/atoms";
@use "~bitstyles/molecules";
@use "~bitstyles/utilities";

How would that work with overrides, can we @foward the configuration for each module?