rename fancybrowser to contentmanipulation

The name "fancybrowser" tricks people into thinking that this is the
reference browser example. But this example is a very simple browser
with an additional fancy content manipulation feature.
Rename this example to contentmanipulation to reflect reality.

Change-Id: I200b701acdc4de1210b550b9f054753e5f1d1ea4
(cherry-pick from eb8eb72e

)
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>