plugins/openscad: migrate to mkVimPlugin

plugins/by-name/openscad/fuzzy-finder-plugin-option.nix

@@ -0,0 +1,50 @@
+{
+  lib,
+  config,
+  pkgs,
+}:
+let
+  optionName = "`settings.fuzzy_finder`";
+
+  fuzzyFinder = config.plugins.openscad.settings.fuzzy_finder;
+
+  defaultPluginName =
+    {
+      skim = "skim-vim";
+      fzf = "fzf-vim";
+    }
+    .${fuzzyFinder} or null;
+
+  default =
+    # If the user has not set `settings.fuzzy_finder`, do not pre-install a fuzzy-finder by default.
+    if fuzzyFinder == null then
+      null
+    # Else, the value of `settings.fuzzy_finder` should be one of the supported options
+    # (`skim` or `fzf`), else he has to provide a value (`null` or a package) to `fuzzyFinderPlugin`.
+    else if defaultPluginName == null then
+      throw ''
+        We cannot automatically select a fuzzy finder plugin from the value given to `${optionName}`: "${fuzzyFinder}".
+        Please, explicitly provide a value to the `plugins.openscad.fuzzyFinderPlugin`:
+          - Either the package for the fuzzy finder plugin to be installed
+          - or `null` if you do not want a plugin to be installed.
+      ''
+    # Case where we automatically select the default plugin to install.
+    else
+      [
+        "vimPlugins"
+        defaultPluginName
+      ];
+
+  defaultText = lib.literalMD ''
+    - `pkgs.vimPlugins.skim-vim` if ${optionName} is `"skim"`
+    - `pkgs.vimPlugins.fzf-vim` if ${optionName} is `"fzf"`
+    - `null` otherwise
+  '';
+in
+lib.mkPackageOption pkgs "fuzzy finder" {
+  nullable = true;
+  inherit default;
+}
+// {
+  inherit defaultText;
+}