fix(i18n): make HasKey aware of newStyleMessages (#7166)
Followup to https://codeberg.org/forgejo/forgejo/pulls/6203
Related to https://codeberg.org/forgejo/forgejo/pulls/6154
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7166
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: 0ko <0ko@noreply.codeberg.org>
Co-committed-by: 0ko <0ko@noreply.codeberg.org>