✨(react) add multi select

Adding this new variant makes necessary to reorganize the files to keep
a clear separations of concerns. As of now Select/index.tsx is just an
entrypoint to render either the mono or multi variant of the select.

packages/react/src/components/Forms/Select/mono-simple.tsx

@@ -0,0 +1,33 @@
+import { useSelect } from "downshift";
+import React from "react";
+import {
+  optionToString,
+  SelectMonoAux,
+  SubProps,
+} from ":/components/Forms/Select/mono-common";
+
+export const SelectMonoSimple = (props: SubProps) => {
+  const downshiftReturn = useSelect({
+    ...props.downshiftProps,
+    items: props.options,
+    itemToString: optionToString,
+  });
+
+  return (
+    <SelectMonoAux
+      {...props}
+      downshiftReturn={{
+        ...downshiftReturn,
+        wrapperProps: downshiftReturn.getToggleButtonProps({
+          disabled: props.disabled,
+        }),
+        toggleButtonProps: {},
+      }}
+      labelAsPlaceholder={!downshiftReturn.selectedItem}
+    >
+      {downshiftReturn.selectedItem && (
+        <span>{optionToString(downshiftReturn.selectedItem)}</span>
+      )}
+    </SelectMonoAux>
+  );
+};