feat: Allow custom precision in Number::currency()

[philharmonie]

This update enhances the Number::currency() method by introducing an optional $precision parameter, allowing developers to specify the number of decimal places when formatting currency values.

Before vs. After:

Previously, the method always used the default precision for each currency, which was sometimes unnecessary or inconsistent with application requirements:

Number::currency(1234.56, in: 'EUR'); // Outputs: "1.234,56 €"
Number::currency(100, in: 'JPY'); // Outputs: "¥100" (Japanese Yen has no decimals by default)

After this update:
Developers can now explicitly set the precision when needed:

Number::currency(1234.56, in: 'EUR', precision: 0); // Outputs: "1.235 €"
Number::currency(1234.56, in: 'EUR', precision: 2); // Outputs: "1.234,56 €"
Number::currency(1234.56, in: 'EUR', precision: 3); // Outputs: "1.234,560 €"
Number::currency(100, in: 'JPY', precision: 2); // Outputs: "¥100.00"

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Benefits to End Users

• Greater flexibility: Developers can now control how currency values are displayed, instead of relying on the formatter’s default precision.
• Better user experience: In some cases, financial applications or reporting tools require rounded values (e.g., whole numbers for invoices).
• Consistency across locales and currencies: Some currencies, like JPY, default to zero decimals, while others like USD default to two. Now, developers can standardize their output.

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Why It Doesn't Break Existing Features

• Backward compatibility: If no precision is provided, the method continues to use the default currency-specific precision.
• No API changes: The method signature remains the same, with an optional additional parameter.
• Relies on NumberFormatter: The change does not override any locale-specific behavior unless explicitly requested by the developer.

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How It Makes Web Development Easier

• Developers no longer need to manually round numbers before passing them to currency(), reducing boilerplate code.
• Web applications that deal with multiple currencies (e.g., e-commerce platforms, finance dashboards) can now enforce consistent display formats without additional logic.
• Works seamlessly with Laravel's internationalization features, making it easier to present localized currency formats without surprises.

[shaedrich]

This really is a popular topic 😂 But hasn't this already been done in #54456?