Server feature list changed and resource updated notifications (#441)

<!-- Provide a brief summary of your changes -->

## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->
Implemented thread-safe notification service following eventual
consistency principle.
Fixes https://github.com/modelcontextprotocol/kotlin-sdk/issues/249
Contracts:
* If the client connection and feature update happened in the same
thread, the timestamps of the events will be consequent
```
server.connect(client)
server.add(feature)
// client will receive the notification
```

```
server.add(feature)
server.connect(client)
// client will NOT receive the notification
```
* If the client connection and feature update happened in the different
threads, both options can be possible

The flow of the notification is explained in the diagram:

<img width="663" height="413" alt="image"
src="https://github.com/user-attachments/assets/e2c4c108-53dd-408d-97ef-97110ce5c979"
/>

Documentation references:

https://modelcontextprotocol.io/specification/2025-06-18/server/prompts#list-changed-notification

https://modelcontextprotocol.io/specification/2025-06-18/server/tools#list-changed-notification

https://modelcontextprotocol.io/specification/2025-06-18/server/resources#list-changed-notification

https://modelcontextprotocol.io/specification/2025-06-18/server/resources#subscriptions

Questions:
* I haven't found the subscription confirmed response message content
docs, how it should look like?

## How Has This Been Tested?
<!-- Have you tested this in a real application? Which scenarios were
tested? -->
Multiple tests with various notification scenarios were added

## Breaking Changes
<!-- Will users need to update their code or configurations? -->

## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed

## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->

kotlin-sdk-server/api/kotlin-sdk-server.api

@@ -82,6 +82,8 @@ public class io/modelcontextprotocol/kotlin/sdk/server/Server {
 	public final fun onConnect (Lkotlin/jvm/functions/Function0;)V
 	public final fun onInitialized (Lkotlin/jvm/functions/Function0;)V
 	public final fun ping (Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
+	public final fun removeNotificationHandler (Lio/modelcontextprotocol/kotlin/sdk/types/Method;)V
+	public final fun removeNotificationHandler (Ljava/lang/String;Lio/modelcontextprotocol/kotlin/sdk/types/Method;)V
 	public final fun removePrompt (Ljava/lang/String;)Z
 	public final fun removePrompts (Ljava/util/List;)I
 	public final fun removeResource (Ljava/lang/String;)Z
@@ -93,6 +95,8 @@ public class io/modelcontextprotocol/kotlin/sdk/server/Server {
 	public final fun sendResourceListChanged (Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public final fun sendResourceUpdated (Ljava/lang/String;Lio/modelcontextprotocol/kotlin/sdk/types/ResourceUpdatedNotification;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public final fun sendToolListChanged (Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
+	public final fun setNotificationHandler (Lio/modelcontextprotocol/kotlin/sdk/types/Method;Lkotlin/jvm/functions/Function1;)V
+	public final fun setNotificationHandler (Ljava/lang/String;Lio/modelcontextprotocol/kotlin/sdk/types/Method;Lkotlin/jvm/functions/Function1;)V
 }
 
 public final class io/modelcontextprotocol/kotlin/sdk/server/ServerOptions : io/modelcontextprotocol/kotlin/sdk/shared/ProtocolOptions {