Support source filter editing

The API for filter is undocumented on the Selfoss API reference, but does exist. We can now allow users setting and modifying filters inside the application.

androidApp/src/main/java/bou/amine/apps/readerforselfossv2/android/UpsertSourceActivity.kt

@@ -65,6 +65,7 @@ class UpsertSourceActivity :
     private fun initFields(items: Map<String, SelfossModel.Spout>) {
         binding.nameInput.setText(existingSource!!.title)
         binding.tags.setText(existingSource!!.tags?.joinToString(", "))
+        binding.filter.setText(existingSource!!.filter)
         binding.sourceUri.setText(existingSource!!.params?.url)
         binding.spoutsSpinner.setSelection(items.keys.indexOf(existingSource!!.spout))
         binding.progress.visibility = View.GONE
@@ -169,6 +170,7 @@ class UpsertSourceActivity :
                                 url,
                                 mSpoutsValue!!,
                                 binding.tags.text.toString(),
+                                binding.filter.text.toString(),
                             )
                         } else {
                             repository.createSource(
@@ -176,6 +178,7 @@ class UpsertSourceActivity :
                                 url,
                                 mSpoutsValue!!,
                                 binding.tags.text.toString(),
+                                binding.filter.text.toString(),
                             )
                         }
                     if (successfullyAddedSource) {