Refactor everything that needs to arrange windows

* The arrange_foo functions are now replaced with arrange_and_commit, or
with manually created transactions and arrange_windows x2.
* The arrange functions are now only called from the highest level
functions rather than from both high level and low level functions.
* Due to the previous point, view_set_fullscreen_raw and
view_set_fullscreen are both merged into one function again.
* Floating and fullscreen are now working with transactions.

include/sway/desktop/transaction.h

@@ -16,12 +16,7 @@
  * the updates all at the same time.
  */
 
-struct sway_transaction {
-	struct wl_event_source *timer;
-	list_t *instructions;   // struct sway_transaction_instruction *
-	list_t *damage;         // struct wlr_box *
-	size_t num_waiting;
-};
+struct sway_transaction;
 
 /**
  * Create a new transaction.