ui5-icon: rtl direction causes icons to be flipped in both directions

[Lukas742]

Describe the bug
Icons implemented in rtl mode are flipped in vertical direction as well.

This is probably caused by transform: scale(-1) as this will flip the element in both directions.

Isolated example
https://codesandbox.io/s/ui5-webcomponents-forked-o7oi0?file=/index.html

Expected behavior
Icons should be mirrored only in horizontal direction, not also in vertical direction.

Screenshots
If applicable, add screenshots to help explain your problem.

Context

• UI5 Web Components version: 1.0.0-rc.11

Affected components (if known)

• Icon