Allow space in sysctl and env metas

[Skazza94]

The current regular expressions used for sysctl and env metas in the Machine class restrict the use of spaces within the value field.

This limitation makes impossible to adjust certain parameters, such as net.ipv4.tcp_rmem, which requires three values:

net.ipv4.tcp_rmem=4096 87380 33554432

Furthermore, users may want to declare environment variables containing spaces.

To address this, we plan to modify the regex to allow spaces while ensuring compliance with the key=value syntax.