fix: Fix missing characters in recorded video

The recording server uses a browser to join the call and records the
browser UI, which renders text like the display name of users or the
name of the Nextcloud instance. By default Firefox provides its own font
but, even if broad, it still has limited character coverage, so the
unsupported characters are shown as ".notdef" glyph (rectangular
boxes).

Fortunately Firefox also uses more complete fonts automatically when
they are available, so now the noto font, which seems to be the most
complete font available in Alpine Linux, is installed and used instead.

Note that "font-noto-cjk" provides regular and bold fonts, while
"font-noto-cjk-extra" provides all weights.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

Containers/talk-recording/Dockerfile

@@ -20,6 +20,9 @@ RUN set -ex; \
         xvfb \
         ffmpeg \
         firefox \
+        font-noto-all \
+        font-noto-cjk \
+        font-noto-cjk-extra \
         bind-tools \
         netcat-openbsd \
         git \