Add formatter option to the VSCode extension

At this point this is an issue for discussing how the formatter can be implemented and how exactly the filter lists and individual rules should be formatted / sorted.

My initial idea is to sort the filter lists so that all rules for a given website were collected together. Something like this:

```
google.com###banner
||example.org^$domain=google.com
||google.com/test
```

At the same time we should take comments into account. Maybe allow grouping rules into a single section using special comments.

Anyways, lets discuss.

CC @AdguardTeam/filters-maintainers @maximtop @scripthunter7