Overhaul parameter getter

[fabianfreyer]

We should probably not filter parameters at this time:

libjail-rs/src/param.rs

Lines 833 to 844 in 1f1e1d9

	// The following parameters are dynamic
	.filter(|name| name != "jid")
	.filter(|name| name != "dying")
	.filter(|name| name != "parent")
	.filter(|name| name != "children.cur")
	.filter(|name| name != "cpuset.id")
	// The following parameters are handled separately
	.filter(|name| name != "name")
	.filter(|name| name != "hostname")
	.filter(|name| name != "path")
	.filter(|name| name != "ip6.addr")
	.filter(|name| name != "ip4.addr")