new project wizard: fix removing all SDKs on new Haxe project creation (IDEA-129284)
Project SDK is lost if any changes are made to platform SDK configuration (IDEA-131812, IDEA-130135)
external build tests: replace incorrect usages of mapNotNull
better comment and assertion
disable one value per file validation when we are enforcing it, avoiding O(NumberOfValues^2) in debug assertions (IDEA-133154)