### What
Skip writing files from the template if the files already exist in the
project directory.
### Why
When I run deno init in a directory that already has a main.ts, or one
of the other template files, I usually want to initialize a workspace
around a file I've started working in. A hard error in this case seems
counter productive. An informational message about what's being skipped
seems sufficient.
Close #20433
The output of `init` are commands, so this should be treated as a "Shell
script". In Shell script, comments must start with `#`, not `//`. (This
also makes the commands example easier to be copied to somewhere.)
This adds an init subcommand to that creates a project starter similar to cargo init.
```
$ deno init my_project
Project initialized
Run these commands to get started:
cd my_project
deno run main.ts
deno run main_test.ts
$ deno run main.ts
Add 2 + 3 5
$ cat main.ts
export function add(a: number, b: number): number {
return a + b;
}
if (import.meta.main) {
console.log("Add 2 + 3", add(2, 3));
}
$ cat main_test.ts
import { assertEquals } from "https://deno.land/std@0.151.0/testing/asserts.ts";
import { add } from "./main.ts";
Deno.test(function addTest() {
assertEquals(add(2, 3), 5);
});
```
Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
