lib: add moduleLocFromOptionString

[stepbrobd]

closes #329

[stepbrobd]

$ rg 'module = "\$\{sources.inputs.nixpkgs\}/nixos/modules'
projects/Agorakit/default.nix
15:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/web-apps/agorakit.nix";

maintainers/templates/project/default.nix
81:      # module = "${sources.inputs.nixpkgs}/nixos/modules/services/web-apps/cryptpad.nix";

projects/Pixelfed/default.nix
26:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/web-apps/pixelfed.nix";

projects/Galene/default.nix
17:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/web-apps/galene.nix";

projects/GNUTaler/default.nix
46:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/finance/taler/module.nix";

projects/SCION/default.nix
50:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/networking/scion/scion.nix";

projects/ntpd-rs/default.nix
28:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/networking/ntp/ntpd-rs.nix";

projects/Forgejo/default.nix
35:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/misc/forgejo.nix";

projects/OpenWebCalendar/default.nix
11:    module = "${sources.inputs.nixpkgs}/nixos/modules/services/web-apps/open-web-calendar.nix";

projects/Mastodon/default.nix
18:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/web-apps/mastodon.nix";

projects/Rosenpass/default.nix
46:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/networking/rosenpass.nix";

projects/Canaille/default.nix
18:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/security/canaille.nix";

projects/Wireguard/default.nix
34:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/networking/wireguard.nix";

projects/Omnom/default.nix
18:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/misc/omnom.nix";

projects/Misskey/default.nix
18:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/web-apps/misskey.nix";

projects/Gancio/default.nix
15:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/web-apps/gancio.nix";

projects/gnunet/default.nix
24:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/networking/gnunet.nix";

projects/Namecoin/default.nix
8:    modules.services.namecoind.module = "${sources.inputs.nixpkgs}/nixos/modules/services/networking/namecoind.nix";
9:    modules.services.ncdns.module = "${sources.inputs.nixpkgs}/nixos/modules/services/networking/ncdns.nix";

projects/Flarum/default.nix
40:      module = "${sources.inputs.nixpkgs}/nixos/modules/services/web-apps/flarum.nix";

[fricklerhandwerk]

Cool, thanks a lot! LGTM

[stepbrobd]

In theory there's a more ergonomic approach (but error message will be very bad if anything wrong happens):

Instead of exposing a function for users to call, this can simply be exported as an attrset that contain option name to file mapping.

IMO this is already ergonomic enough for me 😂