[photos][mob] Trim whitespace from new album name (#6181)

## Description

Previously, newly created albums could easily end with trailing
whitespace, especially when using auto-completion that automatically
adds the next space character. It's not super bad obviously, but I found
it slightly annoying. I can't think of any good reason for why an album
name should ever start or end with whitespace.

## Tests

mobile/lib/ui/collections/album/new_row_item.dart

@@ -35,7 +35,8 @@ class NewAlbumRowItemWidget extends StatelessWidget {
           textCapitalization: TextCapitalization.words,
           popnavAfterSubmission: true,
           onSubmit: (String text) async {
-            if (text.trim() == "") {
+            text = text.trim();
+            if (text == "") {
               return;
             }