AOSP/Email - Bumped the targetSdkVersion to 28 (maximum version) in UnifiedEmail using JobIntentservice.

Bug: 115499280
Bug: 119499886

Test: manual - Ran the following tests on Pixel phone. Tested the email UI.

$ make -j 40
  -rw-r--r-- 1 rtenneti primarygroup 6836038 Feb 19 14:20 out/target/product/marlin/system/product/app/Email/Email.apk

$ make UnifiedEmailTests -j
  -rw-r--r-- 1 rtenneti primarygroup 299415 Feb 19 14:24 out/target/product/marlin/testcases/UnifiedEmailTests/UnifiedEmailTests.apk

$ make EmailTests -j
  -rw-r--r-- 1 rtenneti primarygroup 365023 Feb 19 14:26 out/target/product/marlin/testcases/EmailTests/EmailTests.apk

$ adb install -r out/target/product/marlin/system/product/app/Email/Email.apk
$ adb install -r out/target/product/marlin/testcases/UnifiedEmailTests/UnifiedEmailTests.apk
$ adb install -r out/target/product/marlin/testcases/EmailTests/EmailTests.apk

$ adb shell am instrument -w com.android.email.tests
  Time: 2.719
  OK (157 tests)

Change-Id: I245a490fea999d0594f2d3d4e584ccdc67110866
6 files changed