Refactor hardcoded column sort defaults

sites/+components/tbl-communities.php

@@ -23,7 +23,7 @@
 		return " title='Click to sort by $name.'";
 	}
 
-	// Note: Changing the names displayed requires updating
+	// Note: Changing the names or columns displayed requires updating
 	// the --expanded-static-column-width and --collapsed-static-column-width CSS variables.
 
 	$TABLE_COLUMNS = [
@@ -36,9 +36,11 @@
 		['id' => "server_icon", 'name' => "Host", 'name_long' => "Server host"],
 		['id' => "join_url", 'name' => "URL", 'name_long' => "Join URL (for use in-app)"],
 	];
+
+	$SERVER_ICON_COLUMN = array_keys(array_filter($TABLE_COLUMNS, function($column){return $column['id'] == "server_icon";}))[0];
 ?>
 
-<table id="tbl_communities" data-sort="true" data-sort-asc="true" data-sorted-by="6">
+<table id="tbl_communities" data-sort="true" data-sort-asc="true" data-sorted-by="<?=$SERVER_ICON_COLUMN?>">
 	<tr>
 <?php foreach ($TABLE_COLUMNS as $colno => $column): ?>
 		<th<?=sort_onclick($colno)?> id="th_<?=$column['id']?>" class="tbl_communities__th">