Add complex-numbers exercise

[resu-xuniL]

Hello!
Here is complex-numbers exercise for validation:

• Generate exercice files with configlet create
• Create test and example files
• Set the difficulty rank to 6
• Add GitHub handle to config.json

Is difficulty rank 6 OK?

I'm not really pleased with the 8 last tests:
I had to create the addR subR mulR divR methods to manage a real number.

I looked how the javascript track managed it: they are passing the real number as a complex number (so they can use only 4 methods, one for each arithmetic operation)

    xtest('Subtract real number from complex number', () => {
      const expected = new ComplexNumber(1, 7);
      const actual = new ComplexNumber(5, 7).sub(new ComplexNumber(4, 0));

      expect(actual.real).toBeCloseTo(expected.real);
      expect(actual.imag).toBeCloseTo(expected.imag);
    });

    xtest('Subtract complex number from real number', () => {
      const expected = new ComplexNumber(-1, -7);
      const actual = new ComplexNumber(4, 0).sub(new ComplexNumber(5, 7));

      expect(actual.real).toBeCloseTo(expected.real);
      expect(actual.imag).toBeCloseTo(expected.imag);
    });

Should we do the same thing? i.e. get rid of the 4 methods I created (the ones finishing with a capital R) and keeping only the 4 methods add sub mul div such as in the Javascript track ?

This would gives:

    public function testOperationsBetweenRealNumbersAndComplexNumbersSubtractRealNumberFromComplexNumber(): void
    {
        $realNumber = new ComplexNumbers(4); // --> instead of: $realNumber = 4;
        $ComplexNumber = new ComplexNumbers(5, 7);
        $expected = new ComplexNumbers(1, 7);

        $this->assertEquals($expected, $ComplexNumber->sub($realNumber));
        // --> instead of: $this->assertEquals($expected, $ComplexNumber->subR($ComplexNumber, $realNumber));
    }


    public function testOperationsBetweenRealNumbersAndComplexNumbersSubtractComplexNumberFromRealNumber(): void
    {
        $realNumber = new ComplexNumbers(4); // --> instead of: $realNumber = 4;
        $ComplexNumber = new ComplexNumbers(5, 7);
        $expected = new ComplexNumbers(-1, -7);

        $this->assertEquals($expected, $realNumber->sub($ComplexNumber)); 
        // --> instead of: $this->assertEquals($expected, $ComplexNumber->subR($realNumber, $ComplexNumber));
    }

What do you think ?

[IsaacG]

+cc @exercism/php

[mk-mxp]

@IsaacG It's on the radar, but time is scarce...
@resu-xuniL I'll take a look these days, as soon as time is available.

[homersimpsons]

About CI:

• Test passes for this exercise: https://github.com/exercism/php/actions/runs/35911404438/job/107351853716?pr=1053#step:6:268
• macOS failure are not related to the changes here (will be fixed with 💚 Upgrade macos and windows runners #1056)
• i18n is failing because it is expecting a metadata/php.json in exercism/i18n, I do not really know what is expected here

[IsaacG]

Re: i18n, see exercism/problem-specifications#2686

TL;DR: finalize the PR and get approval first. Once it's ready to merge, a label is used to trigger the translation, which should do a bunch of i18n work and clear the CI.

[homersimpsons]

Everything looks good except for the interface we are proposing to the student. Let's align this with other tracks and it is good to go in my opinion.

Thanks @resu-xuniL

[exercism-i18n]

This PR has been translated 🚀

[homersimpsons]

Merged, thanks @resu-xuniL @IsaacG and @mk-mxp for all your relevant inputs.

Note that I'm rather impressed on how fast the translation went, the French translation looks okay to me exercism/i18n@78e4ebe.