Configure CORS properly

[dsibinski]

For now, all hosts are allowed:

// TODO: configure that properly on prod
app.UseHttpsRedirection();

// TODO: temporary for tests, remove :)
app.UseCors(
    x =>
        x.AllowAnyMethod()
            .AllowAnyHeader()
            .SetIsOriginAllowed(origin => true) // allow any origin
            .AllowCredentials()
); // allow credentials

This task is to remember to change it later.