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"
+}
+```

git-clone/main.tf

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+terraform {
+  required_version = ">= 1.0"
+
+  required_providers {
+    coder = {
+      source  = "coder/coder"
+      version = ">= 0.11"
+    }
+  }
+}
+
+variable "url" {
+    description = "The URL of the Git repository."
+    type        = string
+}
+
+variable "path" {
+  default     = ""
+  description = "The path to clone the repository. Defaults to \"$HOME/<basename of url>\"."
+  type        = string
+}
+
+variable "agent_id" {
+    description = "The ID of a Coder agent."
+    type        = string
+}
+
+resource "coder_script" "git_clone" {
+    agent_id = var.agent_id
+    display_name = "Git Clone"
+    icon = "/icons/git.svg"
+    script = templatefile("${path.module}/run.sh", {
+      CLONE_PATH: var.path != "" ? var.path : join("/", ["~", basename(var.url)]),
+      REPO_URL: var.url,
+    })
+    run_on_start = true
+}

git-clone/run.sh

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+#!/usr/bin/env sh
+
+REPO_URL="${REPO_URL}"
+CLONE_PATH="${CLONE_PATH}"
+# Expand home if it's specified!
+CLONE_PATH="$${CLONE_PATH/#\~/$${HOME}}"
+
+# Check if the variable is empty...
+if [ -z "$REPO_URL" ]; then
+  echo "No repository specified!"
+  exit 1
+fi
+
+# Check if the variable is empty...
+if [ -z "$CLONE_PATH" ]; then
+  echo "No clone path specified!"
+  exit 1
+fi
+
+# Check if `git` is installed...
+if ! command -v git >/dev/null; then
+  echo "Git is not installed!"
+  exit 1
+fi
+
+# Check if the directory exists...
+if [ ! -d "$CLONE_PATH" ]; then
+  echo "Creating directory $CLONE_PATH..."
+  mkdir -p "$CLONE_PATH"
+else
+  echo "$CLONE_PATH already exists, skipping clone!"
+  exit 0
+fi
+
+# Clone the repository...
+echo "Cloning $REPO_URL to $CLONE_PATH..."
+git clone "$REPO_URL" "$CLONE_PATH"
+