.NET: Improve AIAgent and Workflow registrations for DevUI integration (#2227)
* wip
* resolve non-agent workflows as well!
* add tests for devui registrations and resolving
* fixes
* devui for net8 as well!
* simplify TFM
* update tfm...
* tfm rules....
* wip
* roll
* verify entities are registered with a devui call
* tests
* add a proper support for non-keyed workflows
* resolve default aiagent registration
* sort usings :)
* cleanup tests
Korolev Dmitry