Utilities: Extract sorting function

Extracts the function used to sort packages as a utility function so it
can be reused for sorting locales as well.

src/Utilities/sortfn.ts

@@ -0,0 +1,29 @@
+const sortfn = (a: string, b: string, searchTerm: string) => {
+  const x = a.toLowerCase();
+  const y = b.toLowerCase();
+  // check exact match first
+  if (x === searchTerm) {
+    return -1;
+  }
+  if (y === searchTerm) {
+    return 1;
+  }
+  // check for packages that start with the search term
+  if (x.startsWith(searchTerm) && !y.startsWith(searchTerm)) {
+    return -1;
+  }
+  if (y.startsWith(searchTerm) && !x.startsWith(searchTerm)) {
+    return 1;
+  }
+  // if both (or neither) start with the search term
+  // sort alphabetically
+  if (x < y) {
+    return -1;
+  }
+  if (y < x) {
+    return 1;
+  }
+  return 0;
+};
+
+export default sortfn;