refactor: add InitialKeyboard to display before deployment

app/src/main/java/com/osfans/trime/ime/keyboard/InitialKeyboard.kt

@@ -0,0 +1,29 @@
+package com.osfans.trime.ime.keyboard
+
+import android.content.Context
+import android.view.LayoutInflater
+import android.view.View
+import com.osfans.trime.R
+import com.osfans.trime.databinding.InitialKeyboardBinding
+
+/**
+ * Keyboard to be displayed before Rime is deployed completely.
+ *
+ * It displays a loading screen (if deploying) or error message (if cannot deploy).
+ *
+ * TODO: Add a help or info button to show what's problem is behind the scene.
+ */
+class InitialKeyboard(context: Context) {
+    private var binding = InitialKeyboardBinding.inflate(LayoutInflater.from(context))
+
+    fun change(start: Boolean): View  {
+        if (start) {
+            binding.progressBar.setVisibility(View.VISIBLE)
+            binding.deploying.setText(R.string.deploy_progress)
+        } else {
+            binding.progressBar.setVisibility(View.INVISIBLE)
+            binding.deploying.setText(R.string.external_storage_permission_not_available)
+        }
+        return binding.root
+    }
+}

app/src/main/res/layout/input_loading.xml → app/src/main/res/layout/initial_keyboard.xml

@@ -31,4 +31,5 @@
         app:layout_constraintLeft_toLeftOf="parent"
         app:layout_constraintRight_toRightOf="parent"
         />
+
 </androidx.constraintlayout.widget.ConstraintLayout>