idea.sh has been updated in surprising and incompatible ways

As part of JDK-8267706 and related changes, the behavior of idea.sh has changed significantly from the past. The major changes are:

* support for ant file build has been dropped - as a result it is no longer possible to build using IDE actions, or to link jtreg tests to build actions. Additionally, any errors generated during the build are not rendered by the IDE in a way that allow the user to "click" on them and jump at the line at which the error was detected.

* The new project is modularized - that is, it uses IDE modules to mimic JDK modules. I have seen several instances of the IDE complaining of "too many modules", and other similar spurious errors.

Since the original problem which JDK-8267706 aimed to fix was to make path calculation more friendly to environments such as cygwin, I propose to roll back the IDE support to a previously "working" state. If a focussed fix targeted at path problems is submitted on top of that, it's ok, but sweeping changes to the IDE support should at least be discussed in ide-support-dev.