Allow user checkout options on git_worktree_add

Extend the `git_worktree_add_options` to include `git_checkout_options`.

github issue #5949

include/git2/worktree.h

@@ -86,10 +86,15 @@ typedef struct git_worktree_add_options {
 
 	int lock; /**< lock newly created worktree */
 	git_reference *ref; /**< reference to use for the new worktree HEAD */
+
+	/**
+	 * Options for the checkout.
+	 */
+	git_checkout_options checkout_opts;
 } git_worktree_add_options;
 
 #define GIT_WORKTREE_ADD_OPTIONS_VERSION 1
-#define GIT_WORKTREE_ADD_OPTIONS_INIT {GIT_WORKTREE_ADD_OPTIONS_VERSION,0,NULL}
+#define GIT_WORKTREE_ADD_OPTIONS_INIT {GIT_WORKTREE_ADD_OPTIONS_VERSION,0,NULL,GIT_CHECKOUT_OPTIONS_INIT}
 
 /**
  * Initialize git_worktree_add_options structure

src/worktree.c

@@ -405,7 +405,10 @@ int git_worktree_add(git_worktree **out, git_repository *repo,
 		goto out;
 
 	/* Checkout worktree's HEAD */
-	coopts.checkout_strategy = GIT_CHECKOUT_FORCE;
+	if (opts != NULL)
+		memcpy(&coopts, &wtopts.checkout_opts, sizeof(coopts));
+	else
+		coopts.checkout_strategy = GIT_CHECKOUT_FORCE;
 	if ((err = git_checkout_head(wt, &coopts)) < 0)
 		goto out;