add bedrock distribution code (#358)

* add bedrock distribution code

* fix linter error

* add bedrock shields support

* linter fixes

* working bedrock safety

* change to return only one violation

* remove env var reading

* refereshable boto credentials

* remove env vars

* address raghu's feedback

* fix session_ttl passing

---------

Co-authored-by: Dinesh Yeduguru <dineshyv@fb.com>

llama_stack/providers/utils/bedrock/config.py

@@ -0,0 +1,59 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+from typing import Optional
+
+from llama_models.schema_utils import json_schema_type
+from pydantic import BaseModel, Field
+
+
+@json_schema_type
+class BedrockBaseConfig(BaseModel):
+    aws_access_key_id: Optional[str] = Field(
+        default=None,
+        description="The AWS access key to use. Default use environment variable: AWS_ACCESS_KEY_ID",
+    )
+    aws_secret_access_key: Optional[str] = Field(
+        default=None,
+        description="The AWS secret access key to use. Default use environment variable: AWS_SECRET_ACCESS_KEY",
+    )
+    aws_session_token: Optional[str] = Field(
+        default=None,
+        description="The AWS session token to use. Default use environment variable: AWS_SESSION_TOKEN",
+    )
+    region_name: Optional[str] = Field(
+        default=None,
+        description="The default AWS Region to use, for example, us-west-1 or us-west-2."
+        "Default use environment variable: AWS_DEFAULT_REGION",
+    )
+    profile_name: Optional[str] = Field(
+        default=None,
+        description="The profile name that contains credentials to use."
+        "Default use environment variable: AWS_PROFILE",
+    )
+    total_max_attempts: Optional[int] = Field(
+        default=None,
+        description="An integer representing the maximum number of attempts that will be made for a single request, "
+        "including the initial attempt. Default use environment variable: AWS_MAX_ATTEMPTS",
+    )
+    retry_mode: Optional[str] = Field(
+        default=None,
+        description="A string representing the type of retries Boto3 will perform."
+        "Default use environment variable: AWS_RETRY_MODE",
+    )
+    connect_timeout: Optional[float] = Field(
+        default=60,
+        description="The time in seconds till a timeout exception is thrown when attempting to make a connection. "
+        "The default is 60 seconds.",
+    )
+    read_timeout: Optional[float] = Field(
+        default=60,
+        description="The time in seconds till a timeout exception is thrown when attempting to read from a connection."
+        "The default is 60 seconds.",
+    )
+    session_ttl: Optional[int] = Field(
+        default=3600,
+        description="The time in seconds till a session expires. The default is 3600 seconds (1 hour).",
+    )