Add merged commit id on pull view when it's merged (#8062)

options/locale/locale_en-US.ini

@@ -971,6 +971,7 @@ pulls.tab_files = Files Changed
 pulls.reopen_to_merge = Please reopen this pull request to perform a merge.
 pulls.cant_reopen_deleted_branch = This pull request cannot be reopened because the branch was deleted.
 pulls.merged = Merged
+pulls.merged_as = The pull request has been merged as <a rel="nofollow" class="ui sha" href="%[1]s"><code>%[2]s</code></a>.
 pulls.has_merged = The pull request has been merged.
 pulls.title_wip_desc = `<a href="#">Start the title with <strong>%s</strong></a> to prevent the pull request from being merged accidentally.`
 pulls.cannot_merge_work_in_progress = This pull request is marked as a work in progress. Remove the <strong>%s</strong> prefix from the title when it's ready