Support GLib.Array / GLib.PtrArray / GLib.ByteArray in Generator

[badcel]

Unfortunately there are certain GLib array types which need special attention, e.g.:

<array name="GLib.PtrArray" c:type="GPtrArray*">
    <type name="Value"/>
</array>

Those array are different than other arrays as a pointer to a special GPtrArray struct must be provided. This struct contains the length of the array (e.g.: https://docs.gtk.org/glib/struct.PtrArray.html)

If we have some managed data we need to convert it into the corresponding GLib array type. For this to happen the generator must know how to convert the data.

GirModel already differentiates those different types of arrays.

Check if this allows to remove struct arrays safehandles (e.g. ValueArray2OwnedHandle).