Incorrect checkmark icons merged with change #211

[olofh-msft]

The new icons for checkmark:

https://github.com/microsoft/fluentui-system-icons/blob/master/assets/Checkmark/PDF/ic_fluent_checkmark_12_regular.pdf https://github.com/microsoft/fluentui-system-icons/blob/master/assets/Checkmark/PDF/ic_fluent_checkmark_12_filled.pdf

Are incorrect, and don't match at all the larger size icons for "checkmark"

These newer icons should really be called "checked_circle_12_regular" and "checked_circle_12_filled". The actual checkmark icons should not be enclosed in a circle.

Offending change is https://github.com/microsoft/fluentui-system-icons/pull/211