feature: Allow multiple/all locales for isAlpha and IsAlphanumeric decorator

[Alfagun74]

Description

I validate the Name Field using IsAlpha(). German users need Umlauts (ä,ö,ü, etc.), so I've set it to IsAlpha("de-DE"). Now, Spanish users are requesting (ó,ú,á), and tomorrow, Turkish users may request their special characters. I need a solution for this.

Proposed Solution

We can consider using an array of locales to allow, for example, IsAlpha(["de", "es"]), or a more inclusive approach, such as allowing all locales with IsAlpha("all").

Question

Is there a better decorator for handling names? What if the name is Arabic or Chinese, and not Latin at all? I'm quite curious.

Related: #266

[Z4nR]

I thing that is a great idea, so some app or framework using class-validator and have a global user don't need to write every naming styling in decorator

[braaar]

I'm moving this to the discussion tab, as we are trying to keep the issue count low. Please see this issue for an explanation.