Improve Java text-block comment filtering

[Vladyslav-Kuksiuk]

Java text blocks can contain text that looks like line or block comments. Add scanner state for """ text blocks so comment markers inside the text block do not get stripped.

Examples to cover:

String help = """
    Keep this // text.
    Keep this /* text */ too.
    """;

comments="none" should remove real Java comments, but it should keep the
// and /* ... */ text inside the text block.