- dotnet-counters now supports a prefix 'EventCounters\' in front of provider name to force the tool to show EventCounter data when both a Meter and an EventSource have the same name. Without the prefix the Meter data would be shown by default. This is intended to help developers who are migrating between the two and want to see the old data.

- dotnet-counters list command no longer shows a hard-coded list of provider and counter names which was already out-of-date. Instead the command now directs users to the online docs. This should be less work for us and more accurate information for users.

- dotnet-counters console renderer now sorts all providers alphabetically when displaying them. Previously providers that were in the known provider list had special treatment and got sorted first. Several console exporter tests had to be updated because of the sort order change.

- JSON and CSV monitoring tests are re-enabled and use the new EventCounters feature to keep their behavior stable across runtimes given that 9.0 has a System.Runtime Meter and earlier runtimes do not. We already have other tests that handle monitoring Meters and their are tests in the runtime repo for the System.Runtime Meter data.

- CounterSet was deleted and ConfigureCounters() was refactored to use List<EventPipeCounterGroup> instead. CounterSet and EventPipeCounterGroup were already similar abstractions so there wasn't much value in maintaining both of them. EventPipeCounterGroup also supports marking a provider as EventCounter only which was needed for EventCounter prefix support. The counter list parsing tests were updated to validate the same results using the EventPipeCounterGroup API instead.

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Co-authored-by: Mitchell Hwang <16830051+mdh1418@users.noreply.github.com>