Verify caller is cred autofill service

Bug: 370477460
Test: atest CtsAutoFillServiceTestCases:android.autofillservice.cts.inline.InlineLoginMixedCredentialActivityTest
(cherry picked from commit 571a97ad)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:e61320b6fcca1b6f0fe60078cc27fcc844a63f12)
Merged-In: I35f3cf616669a6879fd353876029152e3ce327f1
Change-Id: I35f3cf616669a6879fd353876029152e3ce327f1