reworked autoresize to work with render area

[cxreiff]

The previous autoresize functionality wasn't very flexible, as it was tied to window size as opposed to render_area size. Any layout other than complete fullscreen meant that the dimensions provided by crossterm resize events wouldn't be the same as the area the RatatuiCameraWidget would be rendered in. autoresize_fn was provided as a workaround to adjust the dimensions proportionally after the fact, but it is unnecessary manual work for the user when 99% of the time people just want the render texture to fill the ratatui area Rect that it's being rendered in.

That autoresize functionality has been removed and replaced by a new way to resize each frame: RatatuiCameraWidget::render_autoresize(...).

Just call render_autoresize in your draw function instead of render and any frame where there is a size mismatch, rendering will be skipped and a resize will be triggered instead.