inikulin/parse5

* Simplify testing of parser feedback; fix chunked processing.

Adds task for generation of parser feedback tests in HTML5Lib
tokenization format, so that they can be readable and reusable
instead of generating them in runtime.

Since it's now in the same format as regular tokenization tests,
merged parser_feedback_test logic into tokenizer_test (this
required only extra parameter to be passed around the runner).

Additionally this helped to test parser feedback with chunked
input and identify & fix an error related to extraneous
newlines after hibernation.

* Add pregenerated parser feedback tests.

Added them in a separate commit for cleaner diffs and easier review.