feat(templates): New Go Module template for go.mod files (#884)

New ▸ Go Module creates go.mod with `module $PROJECT_NAME$` and a `go 1.20` directive. The go.mod language, icon and gopls were already registered; only the file template was missing. It also appears in Search Everywhere and Settings ▸ File and Code Templates.

Fixes #882

Co-authored-by: a-rookie-of-C-language <186315048+a-rookie-of-C-language@users.noreply.github.com>

src/features/templates/__tests__/files.test.ts

@@ -70,15 +70,17 @@ describe("file naming", () => {
     expect(withKind(css, kind("css"))).toBe(css);
   });
 
-  it("prefills fixed names (Dockerfile, .editorconfig, .gitignore)", () => {
+  it("prefills fixed names (Dockerfile, .editorconfig, .gitignore, go.mod)", () => {
     for (const [id, name] of [
       ["dockerfile", "Dockerfile"],
       ["editorconfig", ".editorconfig"],
       ["gitignore", ".gitignore"],
+      ["go-mod", "go"],
     ] as const) {
       const t = tpl(id);
       expect(t.defaultName).toBe(name);
-      expect(planFile(t, "/p", t.defaultName!)?.path).toBe(`/p/${name}`);
+      const ext = t.extension ? `.${t.extension}` : "";
+      expect(planFile(t, "/p", t.defaultName!)?.path).toBe(`/p/${name}${ext}`);
     }
   });
 

src/features/templates/files/builtins.ts

@@ -140,6 +140,15 @@ export const BUILTIN_FILE_TEMPLATES: readonly FileTemplate[] = [
       { id: "main", label: "Main", body: "package main\n\nfunc main() {\n\t$END$\n}\n" },
     ],
   },
+  {
+    id: "go-mod",
+    name: "Go Module",
+    icon: "file-gomod",
+    extension: "mod",
+    nameStyle: "asis",
+    defaultName: "go",
+    kinds: [{ id: "module", label: "Module", body: "module $PROJECT_NAME$\n\ngo 1.20\n" }],
+  },
   {
     id: "java",
     name: "Java Class",