Environments now belong to procgroups, modify env_set () and env_get () accordingly

kernel/proc/procgroup.h

@@ -5,6 +5,7 @@
 #include <libk/list.h>
 #include <libk/rbtree.h>
 #include <libk/std.h>
+#include <proc/env.h>
 #include <proc/resource.h>
 #include <sync/spin_lock.h>
 #include <sys/mm.h>
@@ -35,6 +36,7 @@ struct procgroup {
   struct list_node_link* mappings;
   uintptr_t map_base;
   struct procgroup_tls tls;
+  struct proc_env env;
 };
 
 struct procgroup* procgroup_create (void);