Extract chip creation outside of the main chip flow.

This is in preparation of a new version of the chip flow that fully
leverages the new `isHidden` field and enables return animations.

Bug: 202516970
Flag: EXEMPT moving code only
Test: atest CallChipViewModelTest
Change-Id: Ia09a2b34ffce0b0c82ae8faefb84f14c7ce7c66d