Fix whitespace and newline at EOF (#35939)

Summary:
Just a couple of minor fixes in the `template/` folder:

- Remove a trailing space in `rn_edit_text_material.xml` (this was the _only_ trailing space present in a newly generated RN project), which results in the check against the empty tree object failing:
  ```
  $ git diff --check 4b825dc -- template/
  template/android/app/src/main/res/drawable/rn_edit_text_material.xml:23: trailing whitespace.
  +        <!--
  ```
- Add missing newline at end of file in `.watchmanconfig` and `app.json` - Both are text files, and each line (including the last) is expected to end with a newline character (flagged by Git, and also visible as a warning on GitHub):
  <img width="369" alt="image" src="https://user-images.githubusercontent.com/743291/214195867-81c8e622-2130-44d4-bdaf-588e3510c109.png">

## Changelog

[GENERAL] [FIXED] - Fix whitespace and newline at EOF in template

Pull Request resolved: https://github.com/facebook/react-native/pull/35939

Reviewed By: christophpurrer

Differential Revision: D42698256

Pulled By: rshest

fbshipit-source-id: 765fd41d4f501aec578755c754ea0ecb290ae6ca

packages/rn-tester/android/app/src/main/res/drawable/rn_edit_text_material.xml

@@ -20,7 +20,7 @@
        android:insetBottom="@dimen/abc_edit_text_inset_bottom_material">
 
     <selector>
-        <!-- 
+        <!--
           This file is a copy of abc_edit_text_material (https://bit.ly/3k8fX7I).
           The item below with state_pressed="false" and state_focused="false" causes a NullPointerException.
           NullPointerException:tempt to invoke virtual method 'android.graphics.drawable.Drawable android.graphics.drawable.Drawable$ConstantState.newDrawable(android.content.res.Resources)'

template/_watchmanconfig

@@ -1 +1 @@
-{}
+{}

template/android/app/src/main/res/drawable/rn_edit_text_material.xml

@@ -20,7 +20,7 @@
        android:insetBottom="@dimen/abc_edit_text_inset_bottom_material">
 
     <selector>
-        <!-- 
+        <!--
           This file is a copy of abc_edit_text_material (https://bit.ly/3k8fX7I).
           The item below with state_pressed="false" and state_focused="false" causes a NullPointerException.
           NullPointerException:tempt to invoke virtual method 'android.graphics.drawable.Drawable android.graphics.drawable.Drawable$ConstantState.newDrawable(android.content.res.Resources)'

template/app.json

@@ -1,4 +1,4 @@
 {
   "name": "HelloWorld",
   "displayName": "HelloWorld"
-}
+}