[Linting] Check syntax and format code blocks in markdown with blacken-docs

[jond01]

https://github.com/adamchainz/blacken-docs

This change introduces the following benefits:

1. Ensure code blocks in the docs are coherent syntax-wise.
2. Format them according to Black conventions.

Add a new phony target, make fmt-docs, and enforce it as part of make lint, which runs in the CI workflow.

Some examples of wrong syntax in the docs before this PR:

1. Missing closing parenthesis ):
   

   mlrun/docs/monitoring/model-monitoring.md

   Lines 38 to 45 in f72280d

   	```python
   	model_name = "RandomForestClassifier"
   	project.log_model(
   	model_name,
   	model_file="./assets/model.pkl",
   	training_set=train_set,
   	framework="sklearn",
   	```

2. Missing trailing comma , in L61 and L62:
   

   mlrun/docs/data-prep/logging_datasets.md

   Lines 60 to 64 in f72280d

   	# Create a function from py or notebook (ipynb) file
   	get_data_func = project.set_function('./get_data.py'
   	name='get_data'
   	kind='job',
   	image='mlrun/mlrun')

3. Not a Python code block:
   

   mlrun/docs/install/kubernetes.md

   Lines 378 to 380 in f72280d

   	```python
   	s3://<bucket name>/projects/{{run.project}}/artifacts
   	```

4. Function body (... placeholder) unindented:
   

   mlrun/docs/concepts/decorators-and-auto-logging.md

   Lines 80 to 88 in f72280d

   	``` python
   	@mlrun.handler(labels={'framework':'scikit-learn'},
   	outputs=['prediction:dataset'])
   	def train_and_predict(train_data: pd.DataFrame,
   	predict_input: pd.DataFrame,
   	label_column='label'):
   	...
   	```

There are many more wrong syntax examples, but they are all fixed here.

Note: I previously configured Ruff to check and format code blocks inside Python/Jupyter Notebooks, such as code blocks in docstrings.
However, it's not designed to run on markdown files.

[moranbental]

It looks very good, just one comment