Avoid locking Texture/Buffer in trap handler

We generally don't need to lock the `Texture`/`Buffer` in the trap handler, this is particularly problematic now as we hold the lock for the duration of a submission of any workloads. This leads to a large amount of contention for the lock and stalling in the signal handler when the resource may be `Clean` and can simply be switched over to `CpuDirty` without locking and utilizing atomics which is what this commit addresses.

app/src/main/cpp/skyline/gpu/buffer.h

@@ -36,7 +36,9 @@ namespace skyline::gpu {
             Clean, //!< The CPU mappings are in sync with the GPU buffer
             CpuDirty, //!< The CPU mappings have been modified but the GPU buffer is not up to date
             GpuDirty, //!< The GPU buffer has been modified but the CPU mappings have not been updated
-        } dirtyState{DirtyState::CpuDirty}; //!< The state of the CPU mappings with respect to the GPU buffer
+        };
+        std::atomic<DirtyState> dirtyState{DirtyState::CpuDirty}; //!< The state of the CPU mappings with respect to the GPU buffer
+        static_assert(std::atomic<DirtyState>::is_always_lock_free);
 
         bool everHadInlineUpdate{}; //!< Whether the buffer has ever had an inline update since it was created, if this is set then megabuffering will be attempted by views to avoid the cost of inline GPU updates