Fix handle creation on startActionMode

The CL fixes a null pointer exception happening when the selection
controller in Editor is created on startActionMode. The NPE was
introduced by I261559b5c1abe21fd8508ab72f24a5696899a074, which removed
the handle drawable loading before using the drawables for creating the
handles. The current CL adds the handle drawable loading back.

Bug: 119214395
Bug: 119189742
Test: atest CtsWidgetTestCases:android.widget.cts.TextViewTest
Test: atest android.widget.TextViewActivityTest
Test: atest android.widget.TextViewTest
Change-Id: Iba5f6b606b1aaf2124487da5642c6f3b132a061c