Add navigation block markup provided by CBT (#7277)

iotix/parts/header.html

@@ -3,7 +3,7 @@
 <div class="wp-block-group alignwide" style="padding-top:var(--wp--preset--spacing--70);padding-right:0;padding-bottom:var(--wp--preset--spacing--60);padding-left:0"><!-- wp:site-title /-->
 
 <!-- wp:group {"style":{"spacing":{"padding":{"top":"0","right":"0","bottom":"0","left":"0"}}},"layout":{"type":"flex","flexWrap":"nowrap"}} -->
-<div class="wp-block-group" style="padding-top:0;padding-right:0;padding-bottom:0;padding-left:0"><!-- wp:navigation {5} /-->
+<div class="wp-block-group" style="padding-top:0;padding-right:0;padding-bottom:0;padding-left:0"><!-- wp:navigation {"layout":{"type":"flex","justifyContent":"left","orientation":"horizontal"}} /-->
 
 <!-- wp:buttons -->
 <div class="wp-block-buttons"><!-- wp:button {"fontSize":"small"} -->