The IntelliJ files created by idea.sh contain absolute user paths, when they should arguably be using the IntelliJ path variables.

In jdk.iml, we see:
----
<content url="file:///home/david/dev/test/jdk">
  <sourceFolder url="file:///home/david/dev/test/jdk/open/src/java.base/linux/classes" isTestSource="false" />
----
but this is better represented as:
----
<content url="file://$MODULE_DIR$">
  <sourceFolder url="file://$MODULE_DIR$/open/src/java.base/linux/classes" isTestSource="false" />
----

This is easy to test because IntelliJ re-writes the configs to use its variables the first time you open the project, but we should probably be generating them in that form to begin with, as it avoids the project files being absolute in the file system.

There may be some Windows specific work here with \ and /, but it's easy enough either way.