fix(ds/dialog): use existing i18n namespace for close button label (#1776)

DS::Dialog#close_button called I18n.t("common.close") but no
`common.close` key exists in any locale file, so every modal rendered
the literal string "Translation missing: en.common.close" as both the
`title` and `aria-label` of the X close button — visible to screen
readers and as a hover tooltip.

Switch to `ds.dialog.close` to mirror the existing `ds.alert.*`
namespace under config/locales/views/components/*.yml, and add the
English string. Other locales fall back to English (fallbacks=true in
config/application.rb) until translated.

Closes #1763.

Co-authored-by: plind-junior <plind-junior@users.noreply.github.com>

app/components/DS/dialog.rb

@@ -133,8 +133,8 @@ class DS::Dialog < DesignSystemComponent
       variant: "icon",
       class: classes,
       icon: "x",
-      title: I18n.t("common.close"),
-      aria_label: I18n.t("common.close"),
+      title: I18n.t("ds.dialog.close"),
+      aria_label: I18n.t("ds.dialog.close"),
       data: { action: "DS--dialog#close" }
     )
   end

config/locales/views/components/en.yml

@@ -8,6 +8,8 @@ en:
         warning: Warning
         error: Error
         destructive: Error
+    dialog:
+      close: Close
   provider_sync_summary:
     title: Sync summary
     last_sync: "Last sync: %{time_ago} ago"