Add udfpsOverlayParams reference into PromptViewModel

Add reference to udfpsOverlayInteractor.udfpsOverlayParams into
PromptViewModel in order to be able to collect the flow and verify its
value from test

Flag: TEST_ONLY
Bug: 288174226
Test: atest --request-upload-result SystemUIGoogleScreenshotTests:com.android.systemui.biometrics.ui.BiometricPromptScreenshotTest
Change-Id: I256438041104475aee145931c0734fb241d6891a