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/tests/inference/test_text_inference.py

@@ -6,7 +6,6 @@
 
 
 import pytest
-
 from llama_models.llama3.api.datatypes import (
     SamplingParams,
     StopReason,
@@ -15,7 +14,6 @@ from llama_models.llama3.api.datatypes import (
     ToolParamDefinition,
     ToolPromptFormat,
 )
-
 from pydantic import BaseModel, ValidationError
 
 from llama_stack.apis.common.content_types import ToolCallParseStatus
@@ -35,7 +33,6 @@ from llama_stack.apis.models import ListModelsResponse, Model
 
 from .utils import group_chunks
 
-
 # How to run this test:
 #
 # pytest -v -s llama_stack/providers/tests/inference/test_text_inference.py