* Added icons/layers-plus.svg
* Added icons/layers-plus.json
* Update layers-plus.json
fix: updated contributors to reflect actual author
* fix(icon): update layers-plus icon to follow size and spacing guidelines
* fix(icon): adjust layers-plus plus sign alignment and slope
* fix(icon): apply optimized version from reviewer to align on grid and spacing
* chore: add karsa-mistmere as contributor
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Co-authored-by: Eric Fennis <eric.fennis@gmail.com>