[FEATURE] allow choosing the clone-target folder in mcdev join

[JoernBerkefeld]

currently we don't pass in a parameter for the target directory when running git clone and it used to be complicated to clone into the "current" directory.

but as noted here, that's actually quite easy now:

git clone git@github.com:user/my-project.git .

The "dot" makes all the difference.

Going forward, I would add 2 questions to mcdev join:

1. "Which directory should we create your project in?"

• "C:\repos\my-project" (current directory + git repo name)
• "C:\repos" (current directory)
• "C:\repos<your custom subfolder name>" (allows you to enter a folder name

Option 2 would need to be deactivated if that folder is not empty (see isDirEmpty() below).

2. (if option 3 / custom was selected) How would you like to call your subfolder?

• (error on slash/backslash, only allow a-Z, 0-9, -, _)

function isDirEmpty(path) {
    return fs.readdirSync(path).length === 0;
}