Supports numeric ID in /etc/subuid and /etc/subgid .
Fix #40926
Full changes: https://github.com/rootless-containers/rootlesskit/compare/v0.9.4...v0.9.5
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
(cherry picked from commit 17bb5f4b1512309a3eb600efda045539dad6e788)
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>