ui: svg viewbox directive - style not applied on scoped SCSS

[catlabs]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[x] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/NationalBankBelgium/stark/blob/master/CONTRIBUTING.md#got-a-question-or-problem

Current behavior

The svg tag inside the mat-icon doesn't reflect its parent scope.

Expected behavior

We should add the scope to the svg tag

Minimal reproduction of the problem with instructions

Create a page in the showcase, add an icon button and change the width and height on the scoped SCSS

SCSS:
.mat-icon-button { .mat-icon svg { height: 15px; width: 15px; } }

HTML:
<button mat-icon-button><mat-icon starkSvgViewBox svgIcon="heart"></mat-icon></button>

[carlo-nomes]

"Fix starksvgviewbox directive"

[christophercr]

Apparently this issue was caused by the fact that the SvgViewBoxModule was not imported in every module of the Starter