Allow --preset to accept a file path

[JohnnyCrazy]

What problem does this feature solve?

I want to test my local preset-repository and it would be a shame if I had to push everytime. So, for testing and general purposes, it would be nice to also load presets by specifying a path to a local file.

What does the proposed API look like?

so we could either fallback if the preset name is not found, then we could go for:

vue create my_app --preset preset.json

or a more specialized way:

vue create my_app --preset file:preset.json or even vue create my_app --preset-file preset.json

The implementation it self is rather short. When there is an API decision, I could go for a PR.

[yyx990803]

I think we can simply assume it's a file if the value ends in .json. Open to a PR.