httpcaddyfile: Reorder some directives

[francislavoie]

We realized we made some mistakes with the directive ordering, so we're making some minor adjustments.

abort and error don't really make sense to be after other handler directives, because you would expect to be able to "fail-fast" and throw an error before falling through to some file_server or respond typically. So we're moving them up to just before respond, i.e. before the common handler directives.

This is also more consistent with our existing examples in the docs, which actually didn't work due to the directive ordering. See https://caddyserver.com/docs/caddyfile/directives/error#examples (added a test to prove that this example will work now, based on the adapt output)

Also, push doesn't quite make sense to be after handle/route, since its job is to read from response headers to push additional resources if necessary, and handle/route may be terminal so push would not be reached if it was declared outside those. And also, it would make sense to be before templates because a template could add a Link header to the response dynamically.

[mholt]

Thanks, these are good bug fixes. Might come as a surprise to a few users who relied on this buggy ordering, but this is more correct.