Remove persistent non-document reporting from spec.

[clelland]

This change removes the concepts which are only relevant to persistent
out-of-band reporting specs, such as Network Error Logging, and
explicitly defines reporting mechansims for documents, where the
generated reports are queued with the document itself, and thereby
inherit its lifetime. Generic reporting concepts are extracted into
another section so that they can be used by other specs.

Addresses issues raised in #158.

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Preview | Diff

[clelland]

I've updated the deploy scripts to make the rendered artifacts in this branch visible. The core reporting concepts and document-centered reports are at https://w3c.github.io/reporting/split-persistence/index.html, while the persistent network-reports are https://w3c.github.io/reporting/split-persistence/network-reporting.html

[dcreager]

I'm wondering if this patch could go even further. Are there any other specs besides NEL that need persistent out-of-band reporting? If not, an even cleaner refactoring would be to move all of that logic back into NEL proper. No reason to pull it out into a separate "Network Reporting" spec if there's no one else who would use it.

It might still be useful to be able to use Origin Policy to provide default values for the per-document Reporting configuration, but that would also not go in a separate spec; we'd just put the Origin Policy-related text in the main per-document Reporting spec.

So that would leave us with:

1. One "Reporting" spec, which is refactored and simplified to only be used for per-document reporting use cases.

2. "Network Error Logging", which does its own thing since it needs client-side load balancing, failver, retries, etc, to work at all.