added sizedbox, ordinal, roman representation extensions

[athishaves]

Description

Added few extensions which i personally use.

Space -> Converts [num] to [SizedBox].
horizontalSpace for width
verticalSpace for height

Ordinal -> Returns ordinal [String] of [int]

Roman -> Returns roman representation [String] of [int] from 1 to 3999

Issue link

If your PR closes an issue, use the closes keyword followed
by its link, for example:

closes https://github.com/nank1ro/awesome_flutter_extensions/issues/{ISSUE_NUMBER}

replacing {ISSUE_NUMBER} with the number, like: 1

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• 📝 Documentation
• 🗑️ Chore

[nank1ro]

Thanks for your PR, I really appreciate it! 💙
You forgot to export the lib/src/num_ext.dart file from the barrel file.

I have requested some changes.
Please add also unit tests for the ordinal and roman extensions. Thank you!

[nank1ro]

It makes little sense to support negative numbers and turn them into ordinals. If it were necessary, it would suffice to convert it to positive before calling the function.

I would change the implementation into

String get ordinal {
    return switch (this % 100) {
      11 || 12 || 13 => '${this}th',
      _ => switch (this % 10) {
          1 => '${this}st',
          2 => '${this}nd',
          3 => '${this}rd',
          _ => '${this}th'
        }
    };
  }

[nank1ro]

The ordinal function here returns the English suffixes. Specify this in the comments, because it doesn't support localisation.
For example the equivalent of 1st in French is 1er

[nank1ro]

Use a function instead of a getter, because the name is toRoman.
If you want to keep a getter name it without the to.

[nank1ro]

This algorithm could be improved using a map.
What I would write:

 String toRoman() {
    const romanTable = {
      'M': 1000,
      'CM': 900,
      'D': 500,
      'CD': 400,
      'C': 100,
      'XC': 90,
      'L': 50,
      'XL': 40,
      'X': 10,
      'IX': 9,
      'V': 5,
      'IV': 4,
      'I': 1,
    };

    final result = StringBuffer();
    var n = this;
    for (final entry in romanTable.entries) {
      final numeral = entry.key;
      final value = entry.value;
      while (n >= value) {
        result.write(numeral);
        n -= value;
      }
    }
    return result.toString();
  }
}

[athishaves]

Tbh, never knew switch statements can be used like that. Thank you for you time!
I have updated the pr