feat: Add kotlin-sdk-testing module with channel-based transport implementation (#505)

# feat: Add kotlin-sdk-testing module with channel-based transport
implementation

- Introduced `kotlin-sdk-testing` module for testing utilities in the
MCP Kotlin SDK.
- Implemented `ChannelTransport`, providing JSON-RPC transport via
Kotlin coroutines channels.

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

## Motivation and Context
This ChannelTransport can be used for testing Server implementation
without using real transports.

## How Has This Been Tested?
Unit test

## Breaking Changes
No

## Types of changes

- [ ] 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)
- [x] 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

kotlin-sdk-testing/src/jvmTest/resources/junit-platform.properties

@@ -0,0 +1,5 @@
+## https://docs.junit.org/5.3.0-M1/user-guide/index.html#writing-tests-parallel-execution
+junit.jupiter.execution.parallel.enabled=true
+junit.jupiter.execution.parallel.config.strategy=dynamic
+junit.jupiter.execution.parallel.mode.default=concurrent
+junit.jupiter.execution.parallel.mode.classes.default=concurrent

kotlin-sdk-testing/src/jvmTest/resources/simplelogger.properties

@@ -0,0 +1,7 @@
+# Level of logging for the ROOT logger: ERROR, WARN, INFO, DEBUG, TRACE (default is INFO)
+org.slf4j.simpleLogger.defaultLogLevel=INFO
+org.slf4j.simpleLogger.showThreadName=true
+org.slf4j.simpleLogger.showDateTime=false
+
+# Log level for specific packages or classes
+org.slf4j.simpleLogger.log.io.modelcontextprotocol=DEBUG