fix: authorization JSON structure and user-agent

[mmalenic]

Changes

• Adds the user-agent to all internal request inside htsget-rs as otherwise they can get blocked.
  • The user agent is the package name and version.
  • This took a bit of a refactor of the package info, as I wanted the user-agent to be based on the top-level crate that has htsget-config as a dependency. If package_info!() is called inside htsget-config, it will return "htsget-config/<version>" rather than "htsget-lambda/<version>".
• Changes the authorization response structure and gives an "backend" as an alias to the location.

[Copilot]

Pull Request Overview

This PR refactors the HTTP client configuration system and adds user-agent headers to all internal requests, while also updating authorization response structure to include "backend" as an alias for location fields.

Key changes:

• Refactored HTTP client configuration to support late initialization and user-agent injection based on top-level package information
• Added package information propagation through the configuration system to enable proper user-agent headers
• Updated authorization response structure with "backend" alias for location fields

Reviewed Changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
htsget-config/src/config/advanced/mod.rs	Refactored HttpClient to support lazy initialization and user-agent configuration
htsget-config/src/config/mod.rs	Added package_info field and propagation logic throughout configuration
htsget-config/src/http/client.rs	Added user_agent field to HttpClientConfig
htsget-config/src/storage/url.rs	Updated Url storage to use new HttpClient structure
htsget-http/src/middleware/auth.rs	Changed auth methods to mutable to support client building
htsget-http/src/http_core.rs	Added package_info parameter to get/post functions for user-agent propagation
htsget-config/src/config/advanced/auth/response.rs	Added "backend" alias for location fields in authorization responses
htsget-lambda/src/lib.rs	Updated to use new package_info configuration pattern
htsget-axum/src/main.rs	Updated to use new package_info configuration pattern
htsget-actix/src/main.rs	Updated to use new package_info configuration pattern

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