Remove old actions related to External Authentication

[MikeAlhayek]

Remove this

https://github.com/OrchardCMS/OrchardCore/blob/main/src/OrchardCore.Modules/OrchardCore.Users/Controllers/AccountController.cs#L259-L269

also this

OrchardCore/src/OrchardCore.Modules/OrchardCore.Users/Services/ExternalAuthenticationsStartupFilter.cs

Lines 9 to 44 in 4adf49b

	/// <summary>
	/// In version 2.1, the "External Authentication" feature was introduced, necessitating the relocation of all external authentication actions to a new controller.
	/// To maintain backward compatibility, this filter was added to automatically redirect requests from the old path to the new path, ensuring existing users were not impacted.
	///
	/// In version 3.0, this filter should be removed. The following note should be included in the 3.0.0 release notes:
	///
	/// ## Breaking Changes
	/// ### Login View Update
	/// The `ExternalLogin` action has been removed from the `Account` controller.
	/// If you are using a custom `Login.cshtml` view or `Login` template, please update the external login form action.
	/// As of this update, the `ExternalLogin` action has been relocated to the `ExternalAuthentications` controller.
	/// </summary>
	internal sealed class ExternalAuthenticationsStartupFilter : IStartupFilter
	{
	public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
	{
	return builder =>
	{
	builder.Use(async (context, next) =>
	{
	if (context.Request.Method == HttpMethods.Post &&
	context.Request.Path.StartsWithSegments("/OrchardCore.Users/Account/ExternalLogin", StringComparison.OrdinalIgnoreCase))
	{
	context.Request.Path = "/OrchardCore.Users/ExternalAuthentications/ExternalLogin";
	context.Request.RouteValues["controller"] = typeof(ExternalAuthenticationsController).ControllerName();
	context.Request.RouteValues["action"] = nameof(ExternalAuthenticationsController.ExternalLogin);
	context.Request.RouteValues["area"] = "OrchardCore.Users";
	}
	await next();
	});
	next(builder);
	};
	}

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