Add sqlite binary into the docker images

This is done to enable backup functionality in the admin interface while
we're waiting for the libsqlite-sys 0.17 to bubble up in the upstream
dependencies. Then we can start using `VACUUM INTO`

This also extends the check for the sqlite binary to also try `sqlite3`
as this is the name of the binary in baseimage distributions we use.

docker/amd64/postgresql/Dockerfile

@@ -81,6 +81,7 @@ RUN apt-get update && apt-get install -y \
     openssl \
     ca-certificates \
     curl \
+    sqlite3 \
     libpq5 \
     && rm -rf /var/lib/apt/lists/*