Refactor Api-Client

Add Exceptionhandler, AlertService JSON-Converter
AppSettings via DI

Reformat Code

Jugenddienst Stunden/Infrastructure/NullApiClient.cs

@@ -0,0 +1,23 @@
+using Jugenddienst_Stunden.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Jugenddienst_Stunden.Infrastructure;
+
+internal sealed class NullApiClient : IApiClient {
+	private readonly string _message;
+	public NullApiClient(string message) => _message = message ?? "API nicht konfiguriert.";
+
+	public Task<T> GetAsync<T>(string path, IDictionary<string, string?>? query = null, CancellationToken ct = default)
+		=> Task.FromException<T>(new InvalidOperationException(_message));
+
+	public Task<T> SendAsync<T>(HttpMethod method, string path, object? body = null,
+		IDictionary<string, string?>? query = null, CancellationToken ct = default)
+		=> Task.FromException<T>(new InvalidOperationException(_message));
+
+	public Task DeleteAsync(string path, IDictionary<string, string?>? query = null, CancellationToken ct = default)
+		=> Task.FromException(new InvalidOperationException(_message));
+}