Validator should verify that ExtractIcon target contains an icon #2
Description
Currently, the validator considers App\AppInfo\appinfo.ini: [Control]:ExtractIcon as valid if the file exists. However, it should not be considered valid if it does not contain an icon.
As ExtractIcon is only supposed to be used in cases where the icon can't legally be copied to the App\AppInfo\appicon.ico and App\AppInfo\appicon_*.png files, it doesn't necessarily make sense to have it require all of the different icon variants that are supposed to be in appicon.ico, but I suppose if we get #1 working satisfactorily, it wouldn't hurt to check the ExtractIcon target for all of them and warn if some aren't present.