This series has been split up more than the prior two, keeping the non-tests diffs below 200. Hopefully it's easier to review now. If not, please let me know and I can _try_ to split it further, but I'm not sure it can get much more split up than this.
-- v2: uiautomationcore: Add tests for UiaNodeFromHandle. uiautomationcore: Create UI Automation client thread. uiautomationcore: Implement UiaNodeFromHandle. uiautomationcore: Shutdown provider thread when all returned nodes are released. uiautomationcore: Increment module reference count when starting provider thread. uiautomationcore: Implement UiaReturnRawElementProvider.