bounded_threadsafe_queue: Deduplicate and add PushModes

Adds the PushModes Try and Wait to allow producers to specify how they want to push their data to the queue if the queue is full.
If the queue is full:
- Try will fail to push to the queue, returning false. Try only returns true if it successfully pushes to the queue. This may result in items not being pushed into the queue.
- Wait will wait until a slot is available to push to the queue, resulting in potential for deadlock if a consumer is not running.

src/video_core/gpu_thread.cpp

@@ -118,7 +118,7 @@ u64 ThreadManager::PushCommand(CommandData&& command_data, bool block) {
 
     std::unique_lock lk(state.write_lock);
     const u64 fence{++state.last_fence};
-    state.queue.Push(std::move(command_data), fence, block);
+    state.queue.EmplaceWait(std::move(command_data), fence, block);
 
     if (block) {
         Common::CondvarWait(state.cv, lk, thread.get_stop_token(), [this, fence] {