Add possibility to override symbol when using currency format

[PhilippeThouvenot]

I need to override currency symbol to format number without symbol.
But I want to keep the currency formating.
So, for this I have made this pull request to override symbol.

Actually :

\Illuminate\Support\Number::useLocale('fr_CH');
\Illuminate\Support\Number::useCurrency('CHF');

Number::currency(1000000.25, precision: 2);
1 000 000.25 CHF

Number::format(1000000.25, precision: 2);
1 000 000,25

Expected :

Number::currency(1000000.25, precision: 2, symbol: '');
1 000 000.25 

[shaedrich]

Why don't you use normal number formatting?

[PhilippeThouvenot]

You don't have the same resul when normal formating and currency formating.

src/Illuminate/Support/Number.php:190
$formatter = new NumberFormatter($locale ?? static::$locale, NumberFormatter::CURRENCY);

src/Illuminate/Support/Number.php:40
$formatter = new NumberFormatter($locale ?? static::$locale, NumberFormatter::DECIMAL);

The result between us is not the same, check my example.

[shaedrich]

That might be, but shouldn't it be the same? You shouldn't be abusing this method for what it's not supposed to