Add type filtering in appearance page of the admin panel

Prior to this commit, any file type was accepted for header logo,
fav_icon and logo in appearance page in admin panel. This commit
enforces type filtering for these fields.

https://gitlab.com/gitlab-org/gitlab/-/issues/288843

app/views/admin/appearances/_form.html.haml

@@ -19,7 +19,7 @@
               = link_to 'Remove header logo', header_logos_admin_appearances_path, data: { confirm: "Header logo will be removed. Are you sure?"}, method: :delete, class: "btn gl-button btn-danger btn-danger-secondary btn-sm"
             %hr
           = f.hidden_field :header_logo_cache
-          = f.file_field :header_logo, class: ""
+          = f.file_field :header_logo, class: "", accept: 'image/*'
           .hint
             Maximum file size is 1MB. Pages are optimized for a 28px tall header logo
   %hr
@@ -38,7 +38,7 @@
               = link_to 'Remove favicon', favicon_admin_appearances_path, data: { confirm: "Favicon will be removed. Are you sure?"}, method: :delete, class: "btn gl-button btn-danger btn-danger-secondary btn-sm"
             %hr
           = f.hidden_field :favicon_cache
-          = f.file_field :favicon, class: ''
+          = f.file_field :favicon, class: '', accept: 'image/*'
           .hint
             Maximum file size is 1MB. Image size must be 32x32px. Allowed image formats are #{favicon_extension_whitelist}.
             %br
@@ -70,7 +70,7 @@
               = link_to 'Remove logo', logo_admin_appearances_path, data: { confirm: "Logo will be removed. Are you sure?"}, method: :delete, class: "btn gl-button btn-danger btn-danger-secondary btn-sm remove-logo"
             %hr
           = f.hidden_field :logo_cache
-          = f.file_field :logo, class: ""
+          = f.file_field :logo, class: "", accept: 'image/*'
           .hint
             Maximum file size is 1MB. Pages are optimized for a 640x360 px logo.
 

changelogs/unreleased/file_type_filter_admin_appearance.yml

+---
+title: Add type filtering in appearance page of the admin panel
+merge_request: 48709
+author: Paul Ungureanu @ungps
+type: fixed