build: format codebase imports using ruff linter (#1028)

# What does this PR do?

- Configured ruff linter to automatically fix import sorting issues.
- Set --exit-non-zero-on-fix to ensure non-zero exit code when fixes are
applied.
- Enabled the 'I' selection to focus on import-related linting rules.
- Ran the linter, and formatted all codebase imports accordingly.
- Removed the black dep from the "dev" group since we use ruff

Signed-off-by: Sébastien Han <seb@redhat.com>

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan
[Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.*]

[//]: # (## Documentation)
[//]: # (- [ ] Added a Changelog entry if the change is significant)

Signed-off-by: Sébastien Han <seb@redhat.com>

llama_stack/providers/utils/inference/prompt_adapter.py

@@ -13,7 +13,7 @@ import re
 from typing import List, Optional, Tuple, Union
 
 import httpx
-from llama_models.datatypes import is_multimodal, ModelFamily
+from llama_models.datatypes import ModelFamily, is_multimodal
 from llama_models.llama3.api.chat_format import ChatFormat
 from llama_models.llama3.api.datatypes import (
     RawContent,
@@ -47,9 +47,9 @@ from llama_stack.apis.inference import (
     ResponseFormat,
     ResponseFormatType,
     SystemMessage,
+    SystemMessageBehavior,
     ToolChoice,
     UserMessage,
-    SystemMessageBehavior,
 )
 from llama_stack.providers.utils.inference import supported_inference_models