Adds small chevron icons pointing down and right (#843)

* adds small chevron icons pointing down and right

* Optimize SVGs

* Update icons/chevron-down-12.svg

Co-authored-by: Cole Bemis <colebemis@github.com>

* Update icons/chevron-right-12.svg

Co-authored-by: Cole Bemis <colebemis@github.com>

* Optimize SVGs

* Optimize SVGs

* fixes pixel alignment of chevron paths

* Optimize SVGs

Co-authored-by: Mike Perrotti <actions@github.com>
Co-authored-by: Cole Bemis <colebemis@github.com>