Add backend structure with Docker support and initial configuration files

Signed-off-by: Dmitrii <computer@yawaflua.tech>

Took 4 hours 25 minutes

backend/SpMega.Backend/Authetication/JwtAuthenticationSchemeOptions.cs

@@ -0,0 +1,8 @@
+using Microsoft.AspNetCore.Authentication;
+
+namespace SpMega.Backend.Authetication;
+
+public class JwtAuthenticationSchemeOptions : AuthenticationSchemeOptions
+{
+    public const string DefaultScheme = "JwtScheme";
+}