feat(monorepo): use hierarchical workspace layout

[cameronraysmith]

• resolves migrate layout to hierarchical workspace monorepo format #8

[cameronraysmith]

works around

• template instantiation updates package directory name but fails to replace package name in source code #13

by

1. avoiding the use of the package name at all in the simple default root package at src/python-nix-template
2. only exposing the ability to toggle the example monorepo packages on or off but NOT to automatically rename them on instantiation because the source code makes use of the package name whose transformation fails as described in #13

python-nix-template/nix/modules/template.nix

Lines 64 to 69 in 74e0064

	{
	name = "monorepo-package";
	description = "Include the functional programming monorepo package in the project";
	paths = [ "packages/pnt-functional" ];
	value = false;
	}