Accessibility updates - main landmark roles (#17106)

* Removed multiple main tags from home page

Signed-off-by: chaitanyakaranam <chaitanya.karanam@yahoo.com>

* Removed multiple occurances of main in case-studies page

Signed-off-by: chaitanyakaranam <chaitanya.karanam@yahoo.com>

* Replaced css for main tag with .main-section class

Signed-off-by: ChaitanyaKaranam <karanam.krishna.25@gmail.com>

* Added main landmark role for all the pages

Signed-off-by: ChaitanyaKaranam <karanam.krishna.25@gmail.com>

* Force checks.

request-checks: true

layouts/shortcodes/blocks/feature.html

@@ -7,9 +7,9 @@ It can be given a "image" parameter with a name partially matching a file in the
 {{- $imageName := $.Get "image" | default "flower" -}}
 {{ if  $imageName }}{{- template "shortcodes-blocks_getimage" (dict "name" $imageName "ctx" . "target" "feature-image") -}}{{ end }}
 {{- $image := $.Scratch.Get "feature-image" -}}
-<main>
+<div class="main-section">
 	{{ with $image }}<div class="image-wrapper"><img src="{{ .RelPermalink }}" alt="{{ .Title }}"></div>{{ end }}
 	<div class="content">
 		{{ $.Inner }}
 	</div>
-</main>
+</div>