Feature Request: Check instance name upon creation

[Catty2014]

Systemd-nspawn would strip invalid characters in instance name, making ciel unable to operate the container. We could add a check to ensure no invalid character is used in instance name.

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systemd-nspawn会移除实例名里的无效字符，导致ciel不能正确操作容器。可以在创建实例时加一个名称检查来确保没有使用无效字符。

例：BuildCat_la64 会变成 BuildCatla64