Enable eclipse ignoreUnnamedModuleForSplitPackage setting in buildSrc

[philwebb]

On a fresh Eclipse the following needs to be added to .settings/org.eclipse.jdt.core.prefs for buildSrc. We should try and automate that.

org.eclipse.jdt.core.compiler.ignoreUnnamedModuleForSplitPackage=enabled

[wilkinsona]

I think you already tried that in 4aa4e14. My guess is that the settings are getting clobbered by Java Format but that is just a guess. I tried doing this instead:

eclipse.jdt.file.whenMerged {
	def properties = new Properties()
	load(properties)
	properties.setProperty("org.eclipse.jdt.core.compiler.ignoreUnnamedModuleForSplitPackage", "enabled")
	store(properties)
}

It didn't work.

[philwebb]

I thought I'd fixed it previously. I'm not sure why it stopped working.