r-g/f-a: Allow networking for flutter-linux-plugins

Observed issue is:

    ...
    failed with exit code 128, output:
    Downloading assets/Audio.mp3 (122 KB)
    Error downloading object: assets/Audio.mp3 (c0d5157):
    Smudge error: Error downloading assets/Audio.mp3
    (c0d515701793564cd80649c10d5f3b85c24ceb5471a29e8a898b9716921f95c5):
    batch response: Post "https://github.com/meta-flutter/linux_plugins.git/info/lfs/objects/batch":
    dial tcp: lookup github.com: Temporary failure in name resolution
    ...

Relate-to: #3
Relate-to: https://booting.oniroproject.org/rzr/meta-oniro-blueprint-flutter/-/issues/3


Signed-off-by: Philippe Coval <philippe.coval.ext@huawei.com>