feat: add git clone module (#46)

* feat: add `git-clone` module

* Fix script expansion for personalize

* Update README

git-clone/README.md

@@ -0,0 +1,38 @@
+---
+display_name: Git Clone
+description: Clone a Git repository by URL and skip if it exists.
+icon: ../.icons/git.svg
+maintainer_github: coder
+verified: true
+tags: [git, helper]
+---
+# Git Clone
+
+This module allows you to automatically clone a repository by URL and skip if it exists in the path provided.
+
+```hcl
+module "git-clone" {
+    source = "https://registry.coder.com/modules/git-clone"
+    url = "https://github.com/coder/coder"
+}
+```
+
+To use with [Git Authentication](https://coder.com/docs/v2/latest/admin/git-providers), add the provider by ID to your template:
+
+```hcl
+data "coder_git_auth" "github" {
+    id = "github"
+}
+```
+
+## Examples
+
+### Custom Path
+
+```hcl
+module "git-clone" {
+    source = "https://registry.coder.com/modules/git-clone"
+    url = "https://github.com/coder/coder"
+    path = "~/projects/coder/coder"
+}
+```