handle oversized hex in unicode brace-escapes as syntax error - #4477

Parsing an untrusted query with an oversized braced unicode escape throws an internal exception instead of a syntax error:

"\uD83D\u{fffffffff}"  -> java.lang.NumberFormatException at UnicodeUtil.java:53
"\u{fffffffff}"        -> graphql.AssertException: There must be a resource bundle key called InvalidUnicode.invalidHexString

the grammar allows { Hex+ } with any number of digits (EscapedUnicode : Hex Hex Hex Hex | '{' Hex+ '}'), so a value that overflows int reaches Integer.parseInt in parseAndWriteUnicode. the leading escape path catches the NumberFormatException but builds the error with InvalidUnicode.invalidHexString, a key that is missing from every Parsing bundle, so it fails with an AssertException; the trailing-surrogate path (line 53) has no catch at all and leaks the raw NumberFormatException. both should be a normal InvalidSyntaxException.

wrap the trailing parse the same way the leading one is wrapped and add the missing message key to the en/de/nl bundles.