Clean up how we handle identifiers throughout the Boulder codebase by
- moving the Identifier protobuf message definition from sa.proto to
core.proto;
- adding support for IP identifier to the "identifier" package;
- renaming the "identifier" package's exported names to be clearer; and
- ensuring we use the identifier package's helper functions everywhere
we can.
This will make future work to actually respect identifier types (such as
in Authorization and Order protobuf messages) simpler and easier to
review.
Part of https://github.com/letsencrypt/boulder/issues/7311
Make minor, non-user-visible changes to how we structure the probs
package. Notably:
- Add new problem types for UnsupportedContact and
UnsupportedIdentifier, which are specified by RFC8555 and which we will
use in the future, but haven't been using historically.
- Sort the problem types and constructor functions to match the
(alphabetical) order given in RFC8555.
- Rename some of the constructor functions to better match their
underlying problem types (e.g. "TLSError" to just "TLS").
- Replace the redundant ProblemDetailsToStatusCode function with simply
always returning a 500 if we haven't properly set the problem's
HTTPStatus.
- Remove the ability to use either the V1 or V2 error namespace prefix;
always use the proper RFC namespace prefix.