ssd: Move implementation details from ssd.h to ssd-internal.h

- Move private structs and functions to `ssd-internal.h`
- Add `ssd_button_get_type()` and `ssd_button_get_view()`

src/ssd/ssd.c

@@ -10,7 +10,7 @@
 #include "common/mem.h"
 #include "common/scene-helpers.h"
 #include "labwc.h"
-#include "ssd.h"
+#include "ssd-internal.h"
 #include "theme.h"
 #include "view.h"
 
@@ -286,6 +286,18 @@ ssd_hover_state_new(void)
 	return znew(struct ssd_hover_state);
 }
 
+enum ssd_part_type
+ssd_button_get_type(const struct ssd_button *button)
+{
+	return button ? button->type : LAB_SSD_NONE;
+}
+
+struct view *
+ssd_button_get_view(const struct ssd_button *button)
+{
+	return button ? button->view : NULL;
+}
+
 bool
 ssd_debug_is_root_node(const struct ssd *ssd, struct wlr_scene_node *node)
 {