window: Replace meta_window_resize_with_gravity with a frame-rect variant

More low-hanging fruit for our window geometry cleanups...
window: Remove meta_window_move as well

Move to meta_window_move_frame everywhere...
window: Correct the anchoring of drag moving / resizing

Now that meta_window_move_resize and friends act in frame rect
coordinates, we need to convert the initial grab_anchor_window_pos
storage to be in frame rect coordinates as well.
core: Convert GET_FRAME_WIDTH / GET_FRAME_HEIGHT to GET_FRAME_RECT

Since we're going to be calling meta_window_get_frame_rect in here
soon, I'd rather it be one method call, rather than two. We can't
put it at the toplevel, since that might cause infinite recursion
(e.g. meta_core_get calls meta_window_get_frame_rect calls
meta_ui_get_frame_borders calls meta_core_get, ...)
core: Make META_CORE_GET_FRAME_RECT return the "frame rect"

We have two different coordinate spaces here. One is the rectangle
returned by meta_window_get_frame_rect, which is called the "frame
rect" or "the window geometry", which includes visible frame borders
but not invisible frame borders. The other is "frame->rect" which
corresponds to the frame's server geometry. That is, it includes
both visible and invisible frame borders.

These two were of course the same until we introduced invisible
frame borders, and an executive decision was made to make
meta_window_get_frame_rect return the rectangle bounding the
visible portions of the frame.

As time went on, the "frame rect" turned out to be more useful when
making decisions upon, since the user often doesn't think about the
invisible window geometry as part of the window.

We already calculate what amounts to the "frame rect" in the theme
code, so just change META_CORE_GET_FRAME_RECT to consume that
directly.
window: Refactor all move/resize operations to be in frame rect space

For Wayland, we want to have everything possible in terms of the frame
rect, or "window geometry" as the Wayland protocol calls it, in order
to properly eliminate some flashing when changing states to fullscreen
or similar.

For this, we need to heavily refactor how the code is structured, and
make it so that meta_window_move_resize_internal is specified in terms
of the frame rect coordinate space, and transforming all entry points
to meta_window_move_resize_internal.

This is a big commit that's hard to tear apart. I tried to split it
as best I can, but there's still just a large amount of changes that
need to happen at once.

Expect some regressions from this. Sorry for any temporary regression
that this might cause.