Implemented canteen scraper/parser functionality

app/src/main/java/com/denizk0461/studip/fragment/CanteenFragment.kt

@@ -0,0 +1,46 @@
+package com.denizk0461.studip.fragment
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.viewModels
+import com.denizk0461.studip.databinding.FragmentCanteenBinding
+import com.denizk0461.studip.viewmodel.CanteenViewModel
+
+class CanteenFragment : Fragment() {
+
+    private var _binding: FragmentCanteenBinding? = null
+
+    // This property is only valid between onCreateView and
+    // onDestroyView.
+    private val binding get() = _binding!!
+
+    private val viewModel: CanteenViewModel by viewModels()
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
+        _binding = FragmentCanteenBinding.inflate(inflater, container, false)
+        return binding.root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+
+        viewModel.allOffers.observe(viewLifecycleOwner) { offers ->
+            // TODO this must be changed. if an exception is raised, then this will not fire
+            binding.swipeRefreshLayout.isRefreshing = false
+        }
+
+        binding.swipeRefreshLayout.setOnRefreshListener {
+            viewModel.fetchOffers {
+//                binding.swipeRefreshLayout.isRefreshing = false
+            }
+        }
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+}