html-rewriter: Support streaming content replacements (cloudflare#3211)

* Upgrade lol-html to 2.1.0 (changes how C API is accessed)

* html-rewriter: Support streaming content replacements

* Update TS types

Merge pull request cloudflare#3114 from cloudflare/dlapid/refactor_li…

…mitenforcer_workerobserver

Refactor Observer and LimitEnforcer cleaner for...