Fix various width issues

[AydinHassan]

Hopefully this should fix #219. This has taken me all day to fix 😭

Also adds a few utils, debug mode for menu style and mock terminal class for tests.

Going to add a few more tests for the changes regarding width and margins.

[codecov-io]

Codecov Report

Merging #220 into master will increase coverage by <.01%.
The diff coverage is 97.61%.

@@             Coverage Diff              @@
##             master     #220      +/-   ##
============================================
+ Coverage     93.01%   93.02%   +<.01%     
- Complexity      591      606      +15     
============================================
  Files            30       31       +1     
  Lines          1761     1791      +30     
============================================
+ Hits           1638     1666      +28     
- Misses          123      125       +2

Impacted Files	Coverage Δ	Complexity Δ
src/Util/StringUtil.php	100% <100%> (ø)	8 <2> (+2)	⬆️
src/Util/ArrayUtil.php	100% <100%> (ø)	1 <1> (?)
src/MenuStyle.php	96.35% <97.22%> (-0.45%)	76 <6> (+12)

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[AydinHassan]

@jtreminio could you make some tests with PR see if it fixes your problems?

[jtreminio]

This is almost perfect, but the margin is being applied only to left-side:

I've highlighted the scrollbar area on my terminal:

This is with your patch of

    protected function calculateContentWidth() : void
    {
        $this->contentWidth = $this->width
            - ($this->paddingLeftRight * 2)
            - ($this->borderRightWidth + $this->borderLeftWidth)
            - ($this->margin);

        if ($this->contentWidth < 0) {
            $this->contentWidth = 0;
        }
    }

[AydinHassan]

That was the wrong fix actually, it's all related to shrinking the menu width when the terminal is too narrow. Regarding the right margin, yeah we actually don't ever print that because it's obviously empty space, so it never got handled when the terminal is too narrow. Will implement that in another PR.