Note: This is a cherry pick of...

Note: This is a cherry pick of https://googleplex-android-review.googlesource.com/#/c/platform/developers/samples/android/+/2846703/

Update Camera2Basic sample based on feedback during Android App Week.

- Replace android.app.Fragment with v4 support Fragment +
  updated related activity / theme
- Call abortCaptures() to fix bug with multiple image captures after
  pressing the shutter button
- Update copyright dates
- Minor Android Studio warning fixes

Bug: 65302211
Test: Manually ran app before/after changes and verified there were no
regressions.

Change-Id: I735cba5f0d3de091ba86f7fc8d8caf6f8338ebb0
(cherry picked from commit f75e01a8)