Don't use "unfollow language" when cancelling follow requests (#19363)

* Don't use "unfollow language" when cancelling follow requests

- Adds two new i18n keys: `confirmations.cancel_follow_request.confirm`
  and `confirmations.cancel_follow_request.message`
- Update the header container to use new language

* "Withdraw follow request" instead of "cancel follow request"

app/javascript/mastodon/locales/en.json

@@ -20,7 +20,7 @@
   "account.block_domain": "Block domain {domain}",
   "account.blocked": "Blocked",
   "account.browse_more_on_origin_server": "Browse more on the original profile",
-  "account.cancel_follow_request": "Cancel follow request",
+  "account.cancel_follow_request": "Withdraw follow request",
   "account.direct": "Direct message @{name}",
   "account.disable_notifications": "Stop notifying me when @{name} posts",
   "account.domain_blocked": "Domain blocked",
@@ -146,6 +146,8 @@
   "confirmations.discard_edit_media.message": "You have unsaved changes to the media description or preview, discard them anyway?",
   "confirmations.domain_block.confirm": "Block entire domain",
   "confirmations.domain_block.message": "Are you really, really sure you want to block the entire {domain}? In most cases a few targeted blocks or mutes are sufficient and preferable. You will not see content from that domain in any public timelines or your notifications. Your followers from that domain will be removed.",
+  "confirmations.cancel_follow_request.confirm": "Withdraw request",
+  "confirmations.cancel_follow_request.message": "Are you sure you want to withdraw your request to follow {name}?",
   "confirmations.logout.confirm": "Log out",
   "confirmations.logout.message": "Are you sure you want to log out?",
   "confirmations.mute.confirm": "Mute",