✨(react) add the possibility to hide select label

Based on recent feedbacks this feature was needed. It is important for
the label to still be accessible to screen readers, that's why we
introduced the offscreen class.

Resolve #60

packages/react/src/utils/index.scss

@@ -0,0 +1,12 @@
+.c__offscreen {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px;
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  clip-path: inset(50%);
+  white-space: nowrap;
+  border: 0;
+}