Clean up request/response types

[declark1]

Description

Update request/response type names to follow a consistent and improved naming scheme and ensure all endpoints have unique request types to enable implementation of a generic Task<R> type.

• Update request/response types to follow a consistent naming scheme:
  • Use "response" instead of "result" in response type names
  • Use consistent verb tense, e.g. "streaming" instead of "stream"
  • Name should be based on endpoint name components, e.g. GuardrailsHttpRequest is too generic
  • We can omit "detection" for more concise names as it is redundant in this context (everything is detection)
  • Omit "http" and other unnecessary words such as "on" and "with" from names
  • Include modality in name if applicable, e.g. "text" (all endpoints except completions and chat completions)
• Endpoints should have unique request types as this is cleaner and will enable us to use a generic Task<R> wrapper type for Handle implementations (to be implemented in separate issue) instead of separate task types for each endpoint
  • For endpoints that currently share the same request type, implement a newtype wrapper with a std::ops::Deref implementation
  • Reviewed this thread for ideas and think this is the best approach here (only needed for one endpoint currently)

Proposed names:

**DRAFT subject to change based on team feedback