Clean up databinding

[ganadist]

Currently, Android Databinding is maintenance mode,
And using this feature prevents app developers from introducing new functionality or results in degraded build performance.

So, please consider clean up databinding usage on LINE SDK for Android.

Fix #182

Review tip:
For line-sdk/src/main/res/layout/open_chat_info_fragment.xml, there are too many line changes by indent change.

But actual changes are very small.

$ git diff -b 0da582f 525d10b \
    line-sdk/src/main/res/layout/open_chat_info_fragment.xml
diff --git a/line-sdk/src/main/res/layout/open_chat_info_fragment.xml b/line-sdk/src/main/res/layout/open_chat_info_fragment.xml
index d921f77..47bf66b 100644
--- a/line-sdk/src/main/res/layout/open_chat_info_fragment.xml
+++ b/line-sdk/src/main/res/layout/open_chat_info_fragment.xml
@@ -1,17 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
-<layout xmlns:android="http://schemas.android.com/apk/res/android"
+<ScrollView
+    xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
-    tools:context=".openchat.ui.OpenChatInfoFragment">
-
-    <data>
-
-        <variable
-            name="viewModel"
-            type="com.linecorp.linesdk.openchat.ui.OpenChatInfoViewModel" />
-    </data>
-
-    <ScrollView
+    tools:context=".openchat.ui.OpenChatInfoFragment"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:background="@color/openchat_background">
@@ -38,7 +30,6 @@
             android:maxLength="@integer/max_chatroom_name_length"
             android:paddingTop="30dp"
             android:paddingBottom="19dp"
-                android:text="@{viewModel.chatroomName}"
             android:textColor="@color/target_item_text"
             android:textColorHint="@color/text_hint"
             android:textSize="18sp"
@@ -82,7 +73,6 @@
             android:paddingTop="12dp"
             android:paddingBottom="12dp"
             android:inputType="text"
-                android:text="@{viewModel.description}"
             android:textColor="@color/target_item_text"
             android:textColorHint="@color/text_hint"
             android:textSize="15sp"
@@ -222,7 +212,6 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:button="@drawable/list_checkbox_img"
-                    android:checked="@{viewModel.isSearchIncluded}"
                 android:clickable="true"
                 android:focusable="true"
                 app:layout_constraintBottom_toBottomOf="parent"
@@ -230,5 +219,4 @@
                 app:layout_constraintTop_toTopOf="parent" />
         </androidx.constraintlayout.widget.ConstraintLayout>
     </androidx.constraintlayout.widget.ConstraintLayout>
-    </ScrollView>
-</layout>
+</ScrollView>
</details>

[CLAassistant]

All committers have signed the CLA.

[YkSix]

LGTM, thanks.