Support for coverage testing

I'm working on a Bazel-based project that has a goal of enabling code coverage unit testing for our supported languages, one of those languages being C#. However, if I understand correctly, rules_dotnet does not currently support code coverage which puts us in a bind. After spending quite a bit of time investigating how to enable this support without requiring upstream changes to rules_dotnet, we've come to the conclusion that this is likely just not possible (at least not without some very significant compromises and hacky workarounds).

I can go into far more detail of what we're trying to do and how we've tried to do it (I've _almost_ got something working locally with a handful of hacks and a private fork of rules_dotnet), but first I'd like to get initial impressions. Does code coverage support sound possible? Are there plans for it? Any ideas for how it could be done?

The issue names no files, tests, or entry points; start by reviewing the reported rules_dotnet and Bazel coverage constraints. Turn the feasibility question into a concrete scope, with done defined as an agreed implementation path or a documented limitation.

Written by the indexing model from the issue text.