Domains for cosmetic filters should be punycoded during iOS content blocking conversion

[antonok-edm]

The following rule can be converted to iOS content blocking syntax:

przesył-energii.pl##.popular-slider

...but any JSON file including it cannot be loaded in iOS. Instead, after attempting to compile the JSON into a rule store, the following error is produced:

Error Domain=WKErrorDomain Code=6 "(null)" UserInfo={NSHelpAnchor=Rule list compilation failed: Domains must be lower case ASCII. Use punycode to encode non-ASCII characters.}