chore: migrate simple example to a proper project structure (#148)

* feat: migrate simple example to a proper project structure

* test: fix test for simple example

examples/simple-example/README.md

@@ -0,0 +1,45 @@
+# Simple Example
+
+Simple example with `kstreams`
+
+## Requirements
+
+python 3.8+, poetry, docker-compose
+
+### Installation
+
+```bash
+poetry install
+```
+
+## Usage
+
+1. Start the kafka cluster: From `kstreams` project root execute `./scripts/cluster/start`
+2. Inside this folder execute `poetry run app`
+
+The app should publish 5 events with the same payload (i.e. `'{"message": "Hello world!"}'`) to the `local--kstreams-test` topic.
+The `ConsumerRecord` will then be consumed and printed by the consumer.
+
+You should see something similar to the following logs:
+
+```bash
+❯ me@me-pc simple-example % poetry run app
+Topic local--kstreams-test is not available during auto-create initialization
+Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+Group Coordinator Request failed: [Error 15] GroupCoordinatorNotAvailableError
+ConsumerRecord(topic='local--kstreams-test', partition=0, offset=1, timestamp=1702563120133, timestamp_type=0, key='1', value=b'{"message": "Hello world!"}', checksum=None, serialized_key_size=1, serialized_value_size=27, headers=())
+ConsumerRecord(topic='local--kstreams-test', partition=0, offset=2, timestamp=1702563122143, timestamp_type=0, key='1', value=b'{"message": "Hello world!"}', checksum=None, serialized_key_size=1, serialized_value_size=27, headers=())
+ConsumerRecord(topic='local--kstreams-test', partition=0, offset=3, timestamp=1702563124159, timestamp_type=0, key='1', value=b'{"message": "Hello world!"}', checksum=None, serialized_key_size=1, serialized_value_size=27, headers=())
+ConsumerRecord(topic='local--kstreams-test', partition=0, offset=4, timestamp=1702563126172, timestamp_type=0, key='1', value=b'{"message": "Hello world!"}', checksum=None, serialized_key_size=1, serialized_value_size=27, headers=())
+ConsumerRecord(topic='local--kstreams-test', partition=0, offset=4, timestamp=1702563128185, timestamp_type=0, key='1', value=b'{"message": "Hello world!"}', checksum=None, serialized_key_size=1, serialized_value_size=27, headers=())
+```
+
+## Note
+
+If you plan on using this example, pay attention to the `pyproject.toml` dependencies, where
+`kstreams` is pointing to the parent folder. You will have to set the latest version.