freeToBytes
Transfers ownership of the contents of @string to a newly allocated #GBytes. The #GString structure itself is deallocated, and it is therefore invalid to use @string after invoking this function.
Note that while #GString ensures that its buffer always has a trailing nul character (not reflected in its "len"), the returned #GBytes does not include this extra nul; i.e. it has length exactly equal to the "len" member.
Return
A newly allocated #GBytes containing contents of @string; @string itself is freed
Since
2.34