Landscape PIN bouncer: refactor of portrait layout

Portrait layout moved to a separate file and is now included in keyguard_pin_view. This is done in preparation for the implementation of a landscape layout for the pin view where the portrait layout will be referenced multiple times, so the refactor is to avoid code duplication in the future (as the separate portrait layout file can be included multiple times, avoiding duplication).

Bug: 293427037
Test: KeyguardSecurityViewFlipperControllerTest
Change-Id: I5d7c8c02f6c448755cb5726fd9d59524d9f2719a