refactor: Improve spacing behavior for nested layouts with conditional visibility

[kchobantonov]

1. The vertical, horizontal renderers were adding unwanted padding and spacing even when child elements were hidden or not rendered. This caused layout issues with:

• Empty spaces appearing when controls had visible: false
• Excessive padding accumulating in deeply nested layouts
• Inconsistent spacing between visible elements

2. Make the group layout and array layouts/control to use collapsable panels to make it easy to deal with array with large number of elements if we want to collapse the whole array UI into just one row.

3. Make the space usage similar to react - e.g. remove exta margins and/or paddings

4. Other minor fixes

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[kchobantonov]

@sdirix @lucas-koehler please review - new demo example employee-registration

[kchobantonov]

found an issue with horizontal layout when we do not use padding but gap in order to fix the issue with the elements that are invisible because of the security to not have extra space but this breaks when we want to use number of columns in the UI model like

"options": {
    "vuetify": {
      "v-col": [
        {
          "cols": 8
        },
        {
          "cols": 2
        }
      ]
    }
  }

[kchobantonov]

fixing the horizontal and vertical layout by using no-gutters for vertical and fluid for both horizontal and vertical layouts

[kchobantonov]

fix removing extra paddings for invisible elements by not creating the v-col for such elements.

[kchobantonov]

@sdirix @lucas-koehler please review - the pr is ready now

[coveralls]

coverage: 82.798%. remained the same
when pulling 9eabb1b on kchobantonov:fix-layout
into d3662e2 on eclipsesource:master.