Move the helper functions into the Valet namespace

[colindecarlo]

Valet doesn't play well with others.

In its helpers.php file it registers a number of global functions without considering the landscape of the current environment. This leads to fatal errors being raised when Valet redeclares methods that already exist.

To remedy this issue, I've placed the helpers used by Valet in the Valet namespace.

[mattstauffer]

@colindecarlo Hey, could you show how to reproduce the non-merged helpers in a way that causes problems?

[adamwathan]

Problem is all globally installed composer packages share an autoloader, so its very easy to end up with some unrelated package defining the same global function as Valet and breaking Valet for no reason. Have had lots of issues opened around it and until now have recommended using cgr instead of composer but intention has always been to namespace these functions to stop those issues 👍🏻

[mattstauffer]

Ahhhh other globally required things. Great--thanks both! I'll pull it down to test (but looks great) and then merge.