Move sway to desktop/sway and move other packages under programs/sway
up a level to programs/desktop, add niri config to desktop/niri and
refactor common desktop imports into desktop/default.nix that also
imports (for now at least) sway and niri modules
Move wallpapers into programs/desktop since that's where they're
needed anyway
Add helper script to call swaybg with arguments
Make python/default.nix and lua/default.nix to replace
prog/default.nix for each respective language's packages
Move dev tools from prog into emacs/default.nix since that's what
they're relevant for.
Add some extra useful python packages (numpy, scipy, xarray,
matplotlib)
Add yamllint for YAML, associated flymake-yamllint for Emacs, remove
flymake-eslint since I'm not using it
Add lua-language-server and bash-language-server
