remove unused FileUtils.saveText
deprecate and unuse FileContentUtil.setFileText
Revert "[vcs] Add toggle button to hide unregistered roots from the table"

This reverts commit 3ec8e6dcf3efdd9700ed1581f63db0d69f9bef92.

The implementation is buggy, and the need for the button is questionable,
so removing it until explicitly requested.
[log] IDEA-133197 repaint after expanding/collapsing branches

runUnderModalProgress not only runs under a modal progress, but also
prohibits repaint requests (because the graph can be in inconsistent
state while it is changing in the background modal thread) => repaint
request should be done outside of this call.