Move up the check if the editor belongs to the current user

This CL is a preparation for FocusController. It moves up the
editor info package verification. This refactoring is meant to
make the startInput logic move to FocusController easier.

This is just a refactoring CL, no behavior change is expected.

Bug: 314149476
Test: atest CtsInputMethodTestCases InputMethodSystemServerTests
Change-Id: If4eb15e2fce947aafd9f40b0f3f7695e742b306c