Add configurable authlib-injector API path and HTTP support for Yggdrasil auth

Re-implements the changes from PR #2890, adapted for the current codebase
which uses System.Text.Json.Nodes and HttpClient instead of the legacy
Json.JSONData and hand-rolled SslStream HTTP client.

Changes:
- Settings.cs: Convert AuthlibServer from struct to class with
  [TomlDoNotInlineObject]; convert Host to a property that parses
  'host:port' syntax; add AuthlibInjectorAPIPath (default '/api/yggdrasil')
  for servers that use a different prefix (e.g. Drasl uses '/authlib-injector');
  add UseHttps (default true) so local/dev auth servers without TLS work.

- ConfigComments.resx: Add descriptive inline comments for the new
  AuthlibServer fields (Host, Port, AuthlibInjectorAPIPath, UseHttps).

- ProtocolHandler.cs: Replace three hardcoded '/api/yggdrasil/...' paths
  with AuthlibInjectorAPIPath-based paths (authenticate, refresh, join).
  Replace hand-rolled TcpClient+SslStream HTTP in DoHTTPSRequest with
  HttpClient+SocketsHttpHandler (ConnectCallback routes through ProxyHandler).
  Add useHttps parameter so HTTP-only auth servers are supported.

- KeyUtils.cs: Add AuthServerSupportsProfileKeys() that fetches the
  authlib-injector metadata endpoint and checks feature.enable_profile_key.
  Update GetNewProfileKeys() to skip key fetch when the auth server does not
  support profile keys; build the cert URL dynamically using AuthlibInjectorAPIPath
  for Yggdrasil; always fetch real certs instead of returning a dummy response.
  Remove MakeDummyResponse() which is no longer needed.

Tested against a local Drasl instance with authlib-injector 1.2.7 on a
1.21.11 Minecraft server — full auth flow (login, profile key fetch, session
join) confirmed working end-to-end.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

MinecraftClient/Settings.cs

@@ -495,7 +495,7 @@ namespace MinecraftClient
                     [TomlInlineComment("$Main.General.method$")]
                     public LoginMethod Method = LoginMethod.mcc;
                     [TomlInlineComment("$Main.General.AuthlibServer$")]
-                    public AuthlibServer AuthServer = new(string.Empty);
+                    public AuthlibServer AuthServer = new();
 
                     [TomlInlineComment("$Main.General.AuthlibUser$")]
                     public string AuthUser = "";
@@ -709,34 +709,39 @@ namespace MinecraftClient
                         this.Port = Port;
                     }
                 }
-                public struct AuthlibServer
+                [TomlDoNotInlineObject]
+                public class AuthlibServer
                 {
-                    public string Host = string.Empty;
-                    public int Port = 443;
+                    [NonSerialized]
+                    private string _host = string.Empty;
 
-                    public AuthlibServer()
+                    [TomlInlineComment("$AuthlibServer.Host$")]
+                    public string Host
                     {
-                        Host = string.Empty;
-                        Port = 443;
-                    }
-
-                    public AuthlibServer(string Host)
-                    {
-                        string[] sip = Host.Split(new[] { ":", "：" }, StringSplitOptions.None);
-                        this.Host = sip[0];
-
-                        if (sip.Length > 1)
+                        get => _host;
+                        set
                         {
-                            try { this.Port = Convert.ToUInt16(sip[1]); }
-                            catch (FormatException) { }
+                            string[] split = value.Split(new[] { ":", "：" }, StringSplitOptions.None);
+                            if (split.Length >= 1)
+                                _host = split[0];
+                            if (split.Length >= 2)
+                            {
+                                try { Port = Convert.ToUInt16(split[1]); }
+                                catch (FormatException) { }
+                            }
                         }
                     }
 
-                    public AuthlibServer(string Host, ushort Port)
-                    {
-                        this.Host = Host.Split(new[] { ":", "：" }, StringSplitOptions.None)[0];
-                        this.Port = Port;
-                    }
+                    [TomlInlineComment("$AuthlibServer.Port$")]
+                    public int Port = 443;
+
+                    [TomlInlineComment("$AuthlibServer.AuthlibInjectorAPIPath$")]
+                    public string AuthlibInjectorAPIPath = "/api/yggdrasil";
+
+                    [TomlInlineComment("$AuthlibServer.UseHttps$")]
+                    public bool UseHttps = true;
+
+
                 }
             }
         }