We were registering the serializers when we already had a concrete type
on the way into Publish or Send on the .NET side. However, in a xLang
scenario, messages could originate from e.g. Python before being
sent/published from .NET, resulting in no serializer being found.

This change adds a second-change registration and lookup when the agent
is instantiated based on the IHandle<T> implementations.

Unlike with the InProcessRuntime, there is a two-phase initialization,
first when AgentsApp is built (when initial agents are registered) and
when it StartAsync()s and connects to the Gateway. Unfortunately, it is
possible to attempt to send direct RPC calls to the Gateway before the
message channel is opened; in this case, the Gateway has no connected
client corresponding to the RPC's clientId, and falls over.

The fix is to defer registering agents and subscriptions with the
gateway until after the connection is established after .StartAsync() is
called.

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## Why are these changes needed?

<!-- Please give a short summary of the change and the problem this
solves. -->

## Related issue number

<!-- For example: "Closes #1234" -->
Fix #4731 

## Checks

- [ ] I've included any doc changes needed for
https://microsoft.github.io/autogen/. See
https://microsoft.github.io/autogen/docs/Contribute#documentation to
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- [ ] I've added tests (if relevant) corresponding to the changes
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Restoring the grpc + Orleans server into the project

## Why are these changes needed?

This is the distributed agent runtime for .NET that can manage routing
messages amongst a fleet of grpc agent runtimes.

## Related issue number

## Checks

- [ ] I've included any doc changes needed for
https://microsoft.github.io/autogen/. See
https://microsoft.github.io/autogen/docs/Contribute#documentation to
build and test documentation locally.
- [x] I've added tests (if relevant) corresponding to the changes
introduced in this PR.
- [x] I've made sure all auto checks have passed.

---------

Co-authored-by: Jack Gerrits <jack@jackgerrits.com>
Co-authored-by: Jacob Alber <jaalber@microsoft.com>

Stands up an initial implementation of the AgentChat project, including abstractions, base classes, and the `RoundRobinGroupChat` implementation.

Co-authored-by: Jacob Alber <jaalber@microsoft.com>
Co-authored-by: Ryan Sweet <rysweet@microsoft.com>

Co-authored-by: Ryan Sweet <rysweet@microsoft.com>

<img width="1840" alt="Screenshot 2025-01-30 at 6 26 02 PM"
src="https://github.com/user-attachments/assets/5b4c9ebf-0880-4b2e-aa1f-f2b956922b49"
/>

This is in preparation for releasing the Microsoft.AutoGen.Core NuGet
package.

* Moves IHandle<> to Microsoft.AutoGen.Contracts
* Makes KVStringParseHelper internal

* Updates versions of certain dependencies
* Updates NuGet package properties

* Enables deterministic build
* Enables ContinuousIntegrationBuild in CI

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pull request. -->

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assign them to your PR. -->

## Why are these changes needed?

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solves. -->

## Related issue number

<!-- For example: "Closes #1234" -->

## Checks

- [ ] I've included any doc changes needed for
https://microsoft.github.io/autogen/. See
https://microsoft.github.io/autogen/docs/Contribute#documentation to
build and test documentation locally.
- [ ] I've added tests (if relevant) corresponding to the changes
introduced in this PR.
- [ ] I've made sure all auto checks have passed.

Co-authored-by: Jack Gerrits <jack@jackgerrits.com>
Co-authored-by: Ryan Sweet <rysweet@microsoft.com>

Changes `HandlerInvoker` to avoid reflecting for every message when handling arity=2 `IHandler<,>` instances, by moving it out of the final generated delegate.

* Enable configuring SelfDelivery (defaults to false) when using
AgentsAppBuilder
* Also fixes the predicate for self-delivery

---------

Co-authored-by: Griffin Bassman <griffinbassman@gmail.com>

Moves the semantics of message delivery in .NET to be closer to Python
(up to vagaries of differences in Threading)

* Creates a message delivery queue in InProcessRuntime
* Creates Start/Stop/WaitForIdle APIs on InProcessRuntime
* Creates API to step individual messages
* Updates InProcessRuntime to play well with IHost as an IHostedService

formatting

* update getting-started sample

* Fixes issues around SendMessage

* Fixes stackoverflow when calling InMemoryRutnime.RegisterAgentFactoryAsync()