Add get/setExtras to TextLinks and TextSelection

Test: atest frameworks/base/core/tests/coretests/src/android/view/textclassifier/TextSelectionTest.java
Test: atest frameworks/base/core/tests/coretests/src/android/view/textclassifier/TextLinksTest.java
Test: atest cts/tests/tests/view/src/android/view/textclassifier/cts/TextClassifierValueObjectsTest.java

BUG: 118690735

Change-Id: I5786db40b24b38020514f96b1d642835c9a9db51