✨ Ask for target directory when using create-project

[shrink]

The create-project command is used by a lot of projects as part of their installation documentation, for example Symfony, Laravel and Statamic. The create-project command accepts a directory argument which authors of installation instructions must try to convey to readers as being a value the reader must replace with their desired directory.

This Pull Request is for a change to add a new ask option which allows documentation authors to remove any reference to the directory argument and instead have Composer prompt the reader for their target directory. This does not change the default behaviour.

dev:~$ composer create-project symfony/symfony --ask
New project directory [optional]:

Here are a couple of screenshots of the documentation from Symfony, Laravel and Statamic that demonstrate the problem.

Statamic:

Before

After

Symfony:

Laravel:

[Seldaek]

Thanks