Resolves https://github.com/nette/tester/issues/448.

get_debug_type() does not output a null byte for anonymous classes

PHP 8.3 introduced new HTML output of highlight_string(). The main change is that output is wrapped by <pre>, so new lines are preserved (not converted to <br />) and spaces remains spaces (not converted to &nbsp;)

This is handy for environments with non-standard (buffered) handling of
standard output, for example Github Actions (where a progress of tests
cannot be seen until until end-of-line appears, which in standard `console`
mode happens only when all tests finish) or Docker Compose logging output,
where in standard `console` mode each finished test's dot is printed
alone on separate line.

Or the console-lines mode can be handy just to see a more detailed
progress of tests in all environments, because it outputs something
like this:

```
· 1/85 Framework/Assert.contains.phpt OK in 0.14 s
· 2/85 CodeCoverage/PhpParser.parse.edge.phpt OK in 0.17 s
· 3/85 CodeCoverage/PhpParser.parse.lines-of-code.phpt SKIPPED in 0.18 s
· 4/85 CodeCoverage/PhpParser.parse.lines.phpt FAILED in 0.19 s
...
```

Also, "cider mode" now shows a lemon emoji for skipped tests.

Co-authored-by: David Grudl <david@grudl.com>