Add area-chart icon (#1376)

* Add  icon

* Move top line up 1px

* Update paths

* Optimize paths

icons/area-chart.json

@@ -0,0 +1,15 @@
+{
+  "$schema": "../icon.schema.json",
+  "contributors": [
+    "nstokoe"
+  ],
+  "tags": [
+    "statistics",
+    "diagram",
+    "graph",
+    "area"
+  ],
+  "categories": [
+    "charts"
+  ]
+}

icons/area-chart.svg

@@ -0,0 +1,14 @@
+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <path d="M3 3v18h18" />
+  <path d="M7 12v5h12V8l-5 5-4-4Z" />
+</svg>