ofAppGLFWWindow issues & improvements

• ofSetFullscreen queries all the monitor list more than once (two or three times) for different reasons, we can do a monitor callback and store the data there. I already have the code working for using glfwSetMonitorCallback
• There is an erroneous assumption that in macOS you have to set position after setting dimensions in a window, but the issue is that one function calls the other, so I'm proposing setting the window position and dimensions from a rectangle (and getting window rectangle too) https://github.com/openframeworks/openFrameworks/issues/6950
• https://github.com/openframeworks/openFrameworks/issues/6952 - updating GLFW to 3.4.0 fixes some stuff
• when choosing which monitor the fullscreen will appear I think it makes more sense to get the window rectangle center to check, in the case the window is positioned between two displays
• when resizing window to fullscreen the framebuffer appears distorted for one frame. it is easier to see with low framerates like 6 fps. I think this is related as how the viewport is updated only in new frames.
• it seems there is no need to call clear on currentRenderer when getBackgroundAuto() == false now. even if it was needed it could be called on resize_cb and not in the third frame after window resized, as it is now.
• framebuffer_size_cb calls resize_cb but it is redundant from what I've seen.
• If you start a software in fullscreen and toggle fullscreen it never recover dimensions
  More about this: in setup if your window is set to fullscreen the window settings are set to the fullscreen size like this:

		auto size = getScreenSize();
		settings.setSize(size.x, size.y);

and windowmode is forcefully set to OF_WINDOW in order to trigger the setFullscreen function, if target and settings are the same, the function returns

		settings.windowMode = OF_WINDOW;

and this act overwrites the settings.setSize original values.
this can be easily solved by different ways, my suggestion is a second optional parameter in setFullScreen

	void		setFullscreen(bool fullscreen, bool force = false);

which allows OF_FULLSCREEN to be set, even when settings already have the same value

Question: is there a situation where the framebuffer dimensions are different than the window dimensions? I thought it was for different retina resolutions but they are always the same here.

Start at ofAppGLFWWindow and trace the fullscreen, window rectangle, monitor callback, resize_cb, framebuffer_size_cb, and renderer-clear paths described in the checklist. Reproduce the fullscreen toggle, monitor selection, resize, and low-framerate cases, then use the linked issues 6950 and 6952 for related context. Done means the agreed windowing and framebuffer issues are resolved and the listed cases behave correctly.