Show default filename in history-downloads.php if none

Right now, if the store owner doesn't put a Name on the deliverable file(s), it triggers an error on the account pages using history-downloads.php

I recommend setting it to default to the name given if no filename was provided by changing line 59 from this:

<?php echo esc_html( $file['name'] ); ?>

to this:

<?php echo isset( $file['name'] ) ? esc_html( $file['name'] ) : esc_html( $name ); ?>

Signed-off-by: Phil Johnston <support@mintplugins.com>