Move systemtags icon to icons.scss

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

apps/systemtags/css/systemtagsfilelist.scss

@@ -12,10 +12,6 @@
 	margin-left: 10px;
 }
 
-.nav-icon-systemtagsfilter {
-	@include icon-color('tag', 'systemtags', $color-black);
-}
-
 #app-sidebar .mainFileInfoView .tag-label {
 	cursor: pointer;
 	padding: 13px;

apps/systemtags/img/tag.svg

@@ -1 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" height="16" width="16" version="1" viewBox="0 0 16 16"><path color="#000" fill="none" d="M-62.897-32.993h163.31v97.986h-163.31z"/><path d="M6.186.96L1.38.975c-.273 0-.347.21-.348.346l-.015 4.802 8.723 8.722a.498.498 0 0 0 .71 0l4.456-4.457a.5.5 0 0 0 .002-.71v.01L6.54 1.318 6.186.964zM4.02 2.814a1.144 1.144 0 0 1 1.143 1.144A1.144 1.144 0 0 1 4.02 5.1a1.144 1.144 0 0 1-1.145-1.143A1.144 1.144 0 0 1 4.02 2.813z"/></svg>

core/css/icons.scss

@@ -479,7 +479,10 @@ img, object, video, button, textarea, input, select, div[contenteditable='true']
 	@include icon-color('search', 'actions', $color-black, 1, true);
 }
 
-
 .icon-talk {
 	@include icon-color('app-dark', 'spreed', $color-black, 1);
 }
+
+.nav-icon-systemtagsfilter {
+	@include icon-color('tag', 'actions', $color-black, 1, true);
+}