[9.x] Str::squish trim ZWNBSP

[allowing]

#41949

[nshiro]

@allowing
Hello! I saw your comment today.

Nice PR, but I am a little confused.
I thought this squish is supposed to cut spaces from the string in the middle, too.
If so, don't we need "ZWNBSP" in the first preg_replace() too for consistency ?

#41791
#41877
#41924

[allowing]

@nshiro
嗯对的，第一个也应该加上。感谢你的提醒。

其实通过枚举的方式来实现，有点Hack的味道。没办法，'\s'并不完全包含不可见字符。

Well yes, the first one should also be added. Thank you for your reminder.

In fact, it is implemented by enumeration, which is a bit like Hack. No way, '\s' doesn't exactly contain invisible characters.

[allowing]

Oh!

The ZWNBSP cannot be replaced with spaces. Because it's called Zero Width No-Break SPace. It doesn't take up space.

[nshiro]

Ah, things are not so simple.. 😢