Improve error message for 'package-registry publish' (#6576)

* Improve error message for 'package-registry publish'

Motivation:
When registry publish fails with client error, the current error message is "Error: failed publishing: invalid registry response status '400', expected '[201, 202]'", which doesn't provide much information on what went wrong.

rdar://109410245

Modifications:
- Wrap 4xx status response in `RegistryError.clientError` and 5xx in `RegistryError.serverError`. Both errors include response body as details.
- Change `package-registry publish` to throw the wrapped `clientError` such that more details (i.e., response body) get displayed.

* Don't lose failedPublishing context

Author: yim-lee

Sources/PackageRegistry/RegistryClient.swift

@@ -1611,9 +1611,14 @@ public final class RegistryClient: Cancellable {
             return RegistryError.unauthorized
         case 403:
             return RegistryError.forbidden
+        case 400...499:
+            return RegistryError.clientError(
+                code: response.statusCode,
+                details: response.body.flatMap { String(data: $0, encoding: .utf8) } ?? ""
+            )
         case 501:
             return RegistryError.authenticationMethodNotSupported
-        case 500, 502, 503:
+        case 500...599:
             return RegistryError.serverError(
                 code: response.statusCode,
                 details: response.body.flatMap { String(data: $0, encoding: .utf8) } ?? ""
@@ -1673,6 +1678,7 @@ public enum RegistryError: Error, CustomStringConvertible {
     case failedPublishing(Error)
     case missingPublishingLocation
     case serverError(code: Int, details: String)
+    case clientError(code: Int, details: String)
     case unauthorized
     case authenticationMethodNotSupported
     case forbidden
@@ -1771,6 +1777,8 @@ public enum RegistryError: Error, CustomStringConvertible {
             return "response missing registry source archive"
         case .serverError(let code, let details):
             return "server error \(code): \(details)"
+        case .clientError(let code, let details):
+            return "client error \(code): \(details)"
         case .unauthorized:
             return "missing or invalid authentication credentials"
         case .authenticationMethodNotSupported:

Sources/PackageRegistryTool/PackageRegistryTool+Publish.swift

@@ -22,8 +22,8 @@ import Workspace
 @_implementationOnly import X509 // FIXME: need this import or else SwiftSigningIdentity initializer fails
 
 import struct TSCBasic.ByteString
-import struct TSCBasic.SHA256
 import struct TSCBasic.RegEx
+import struct TSCBasic.SHA256
 
 import struct TSCUtility.Version