refactor(icons): cleaned icons, favicons, and logos

Also bumped version from `1.5.12` to `1.6.0`

Author: bkader

css/admin.css

@@ -2504,7 +2504,7 @@ table td>input[type="checkbox"] {
 	block-size: 1.5rem;
 	inline-size: 1.5rem;
 	background-color: transparent;
-	background-image: url("../img/skeleton-white.png");
+	background-image: url("../img/icon-white.png");
 	background-repeat: no-repeat;
 	background-position: center center;
 	color: inherit;
@@ -2858,7 +2858,7 @@ table td>input[type="checkbox"] {
 
 .csk-admin.csk-login .footer .skeleton-footer-logo {
 	background-color: transparent;
-	background-image: url("../img/skeleton-white.png");
+	background-image: url("../img/icon-white.png");
 	background-position: center center;
 	background-repeat: no-repeat;
 	block-size: 1.5rem;