compose: Add keyboard shortcut tooltip to Drafts link..
compose: Add keyboard shortcut tooltip to Drafts link..

This is for consistency with how we indicate keyboard shortcuts in
other elements in the compose area.

Fixes: #22131.
zulip/zulip,rht/zulip,rht/zulip,rht/zulip,zulip/zulip,rht/zulip,andersk/zulip,rht/zulip,rht/zulip,zulip/zulip,andersk/zulip,rht/zulip,zulip/zulip,zulip/zulip,zulip/zulip,andersk/zulip,andersk/zulip,andersk/zulip,zulip/zulip,andersk/zulip,andersk/zulip