When the compose box is closed, if the selected message is for the
direct conversation with the current user, then we show "Message
yourself" as the compose reply button text.
Adds `decode_dm_recipients_user_ids_from_url` helper function to
hash_util, which parses a narrow URL for DM recipient user IDs.
Checks that "dm" operand, which should be a string of user emails,
also passes the check for all the email addresses being valid
compose recipients.
Co-Authored-By: Lauryn Menard <lauryn@zulip.com>
This commit unifies translation strings for reply button label
to reduce translation effort.
Both the `has_empty_string_topic` and other cases now use a single
"Message <z-recipient-label></z-recipient-label>"`, with dynamic
content passed appropriately.
