Add string helper to get initials from a string

[denjaland]

This PR introduces the support for retrieving the initials from a string, optionally capitalizing the string:

Str::initials('mickey mouse');       // mm
Str::initials('mickey mouse', true); // MM

It also introduces fluent API support:

new Stringable('mickey mouse')->initials();          // mm
new Stringable('mickey mouse')->initials()->upper(); // MM

[shaedrich]

Technically, you could simplify this to just

Suggested change

	$parts = mb_split("\s+", $value);
	$parts = array_map(fn ($part) => mb_substr($part, 0, 1), $parts);
	$initials = implode('', $parts);
	$initials = trim(preg_replace('/\b([[:alpha:]]).*?\b(?:\s+)?/', '$1', $value));

[denjaland]

Hmm. I agree you can probably try and go down that route, but I followed the current style of the other helpers in the class. And to me personally, the intent of what my three lines do is much more clearer to a developer than having to see what yours does. (clever is not always clearer)

Also - your version isn't multibyte safe. Running that using the string "über eats'" would return übe" whereas mine returns "üe" as per expectation.

[shaedrich]

I didn't try to be clever, I just wanted to avoid unnecessary split/implode + mapping when you just want to extract something and do not care about the rest.

Sure, the suggestion can be improved like with mb_ereg() and or replacing [[:alpha:]] with something more suiting.

[denjaland]

I didn't say you were trying to be clever - at least that's not what I intended. I just prefer - in general - code that is immediately clear to the developer/reader of the code. It's just personal flavour/taste. No worries.

I'm just going to leave the PR as is and see whether it gets merged - feel free to suggest changes though