add material you

[Annabefish]

Dear @SubhamTyagi , I'm Annabefish. I recently worked on issue #142
To achieve the function that default theme will change according to the settings in Android system, I modified following files.

1. LauncherActivity.java : extended AppCompatActivity( I saw the comment that the reason you didn't extend it is to make apk small, but I haven't come up with other solutions yet)
2. Last-Launcher/build.gradle: I add some lines to use checkstyle which can see if the codes I add are canonical
3. App/build.gradle: Changed the versions, so if running with android studio, the android sdk 12 is needed. And added two dependencies.
4. Flowlayout/layouts/build.gradle:Changed the versions, so if running with android studio, the android sdk 12 is needed.
5. style.xml:<style name="AppBaseTheme" parent="Theme.MaterialComponents.DayNight">
6. AndroidManifest.xml:android:exported="true"

Looking forward to your reply!
Yours ,
Annabefish