Deploy token access for the Conan Package Registry

What does this MR do?

This MR updates the Conan package manager API endpoints to allow deploy tokens as a valid credential type.

Conan authentication uses the standard api_guard #find_user_from_sources API authentication flow, but it overrides a few of the methods due to the need for decoding and encoding a special JWT. That logic is handled in ConanToken. This MR adds an additional step to the existing flow to check for deploy tokens in addition to personal access tokens and job tokens.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related #213566 (closed)